BAC end sequences and a physical map reveal transposable element content and clustering patterns in the genome of Magnaporthe grisea

Transposable elements (TEs) are viewed as major contributors to the evolution of fungal genomes. Genomic resources such as BAC libraries are an underutilized resource for studying genome-wide TE distribution. Using the BAC end sequences and physical map that are available for the rice blast fungus, Magnaporthe grisea, we describe a likelihood ratio test designed to identify clustering of TEs in the genome. A significant variation in the distribution of three TEs, MAGGY, MGL, and Pot2 was observed among the fingerprint contigs of the physical map. We utilized a draft sequence of M. grisea chromosome 7 to validate our results and found a similar pattern of clustering. By examining individual BAC end sequences, we found evidence for 11 unique integrations of MAGGY or MGL into Pot2 but no evidence for the reciprocal integration of Pot2 into another TE. This suggests that: (a) the presence of Pot2 in the genome predates that of the other TEs, (b) Pot2 was less transpositionally active than other TEs, or (c) that MAGGY and MGL have integration site preference for Pot2. High transition/transversion mutation ratios as well as bias in transition site context was observed in MAGGY and MGL elements, but not in Pot2 elements. These features are consistent with the effects of a Repeat-Induced Point (RIP) mutation-like process occurring in MAGGY and MGL elements. This study illustrates the general utility of a physical map and BAC end sequences for the study of genome-wide repetitive DNA content and organization.     

Identification of sialoadhesin as a dominant lymph node counter-receptor for mouse macrophage galactose-type C-type lectin 1

In the sensitization phase of contact hypersensitivity in mice, dermal macrophages (MOs) expressing MO galactose-type C-type lectin1 (MGL1) are known to migrate from the dermis to lymph nodes (LNs) where they accumulate in the subcapsular sinus, interfollicular regions, and areas surrounding high endothelial venules. We hypothesize that the interactions between MGL1 and its ligands determine the localizations of MGL1-positive cells within the LNs. In the present study, our major aim was to isolate MGL1 counter-receptor(s) from lysates of LNs using affinity chromatography with immobilized recombinant MGL1. Fractions bound and eluted with EDTA were analyzed by SDS-PAGE and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. One of the predominant components was sialoadhesin (Sn, Siglec-1). Sn from lysates of LNs was immobilized on microtiter plates precoated with anti-Sn monoclonal antibody, and binding of recombinant MGL1 and adhesion of cells expressing MGL1 were tested. The binding of recombinant MGL1 to Sn was shown to be dependent on Ca2+ and N-glycans on Sn. MGL1-transfected Chinese hamster ovary cells adhered to the Sn-coated plates, whereas mock transfectants did not. Immunohistochemical localization of anti-Sn monoclonal antibody in LN coincided with the subcapsular sinus area to which recombinant MGL1 was bound. Furthermore, the distribution of MGL1+ cells after sensitization with FITC was demonstrated to overlap with that of Sn within the subcapsular sinus of draining LNs. These results suggest that Sn acts as an endogenous counter-receptor for MGL1.     

Mapping of avirulence genes in the rice blast fungus, Magnaporthe grisea, with RFLP and RAPD markers

Three genetically independent avirulence genes, AVR1-Irat7, AVRI-MedNoi; and AVR1-Ku86, were identified in a cross involving isolates Guy11 and 2/0/3 of the rice blast fungus, Magnaporthe grisea. Using 76 random progeny, we constructed a partial genetic map with restriction fragment length polymorphism (RFLP) markers revealed by probes such as the repeated sequences MGL/MGR583 and Pot3/MGR586, cosmids from the M. grisea genetic map, and a telomere sequence oligonucleotide. Avirulence genes AVR1-MedNoi and AVR1-Ku86 were closely linked to telomere RFLPs such as marker TelG (6 cM from AVR1-MedNoi) and TelF (4.5 cM from AVR1-Ku86). Avirulence gene AVR1-Irat7 was linked to a cosmid RFLP located on chromosome 1 and mapped at 20 cM from the avirulence gene AVR1-CO39. Using bulked segregant analysis, we identified 11 random amplified polymorphic DNA (RAPD) markers closely linked (0 to 10 cM) to the avirulence genes segregating in this cross. Most of these RAPD markers corresponded to junction fragments between known or new transposons and a single-copy sequence. Such junctions or the whole sequences of single-copy RAPD markers were frequently absent in one parental isolate. Single-copy sequences from RAPD markers tightly linked to avirulence genes will be used for positional cloning.     

Carbohydrate binding mechanism of the macrophage galactose-type C-type lectin 1 revealed by saturation transfer experiments

Macrophage galactose-type C-type lectins 1 and 2 (MGL1/2) are expressed on the surfaces of macrophages and immature dendritic cells. Despite the high similarity between the primary sequences of MGL1 and MGL2, they display different ligand specificities. MGL1 shows high affinity for the LewisX trisaccharide, whereas MGL2 shows affinity for N-acetylgalactosamine. To elucidate the structural basis for the ligand specificities of the MGLs, we performed NMR analyses of the MGL1-LewisX complex. To identify the LewisX binding site on MGL1, a saturation transfer experiment for the MGL1-LewisX complex where sugar-CH/CH2-selective saturation was applied was carried out. To obtain sugar moiety-specific information on the interface between MGL1 and the LewisX trisaccharide, saturation transfer experiments where each of galactose-H5-, fucose-CH3-, and N-acetylglucosamine-CH3-selective saturations was applied to the MGL1-LewisX complex were performed. Based on these results, we present a LewisX binding mode on MGL1 where the galactose moiety is bound to the primary sugar binding site, including Asp-94, Trp-96, and Asp-118, and the fucose moiety interacts with the secondary sugar binding site, including Ala-89 and Thr-111. Ala-89 and Thr-111 in MGL1 are replaced with arginine and serine in MGL2, respectively. The hydrophobic environment formed by a small side chain of Ala-89 and a methyl group of Thr-111 is a requisite for the accommodation of the fucose moiety of the LewisX trisaccharide within the sugar binding site of MGL1.     

Retardation of removal of radiation-induced apoptotic cells in developing neural tubes in macrophage galactose-type C-type lectin-1-deficient mouse embryos

MGL1/CD301a is a C-type lectin that recognizes galactose and N-acetylgalactosamine as monosaccharides and is expressed on limited populations of macrophages and dendritic cells at least in adult mice. In this study, pregnant mice with Mgl1+/- genotype were mated with Mgl1+/- or Mgl1-/- genotype males, and the embryos were used to assess a hypothesis that this molecule plays an important role in the clearance of apoptotic cells. After X-ray irradiation at 1 Gy of developing embryos at 10.5 days post coitus (d.p.c.), the number of Mgl1-/- pups was significantly reduced as compared with Mgl1+/+ pups. Distributions of MGL1-positive cells, MGL2-positive cells, and apoptotic cells were histologically examined in irradiated Mgl1+/+ embryos. MGL1-positive cells were detected in the neural tube in which many cells undergo apoptosis, whereas MGL2-positive cells were not observed. Biotinylated recombinant MGL1 bound a significant portion of the apoptotic cells. When Mgl1+/+ and Mgl1-/- embryos were examined for the presence of apoptotic cells, similar numbers of apoptotic cells gave rise, but the clearance of these cells was slower in Mgl1-/- embryos than in Mgl1+/+ embryos. These results strongly suggest that MGL1/CD301a is involved in the clearance of apoptotic cells. This process should be essential in the repair and normal development of X-ray-irradiated embryos.     

The Macrophage Galactose-Type Lectin Can Function as an Attachment and Entry Receptor for Influenza Virus

Specific protein receptors that mediate internalization and entry of influenza A virus (IAV) have not been identified for any cell type. Sialic acid (SIA), the primary attachment factor for IAV hemagglutinin, is expressed by numerous cell surface glycoproteins and glycolipids, confounding efforts to identify specific receptors involved in virus infection. Lec1 Chinese hamster ovary (CHO) epithelial cells express cell surface SIA and bind IAV yet are largely resistant to infection. Here, we demonstrate that expression of the murine macrophage galactose-type lectin 1 (MGL1) by Lec1 cells enhanced Ca²⁺-dependent IAV binding and restored permissivity to infection. Lec1 cells expressing MGL1 were infected in the presence or absence of cell surface SIA, indicating that MGL1 can act as a primary receptor or as a coreceptor with SIA. Lec1 cells expressing endocytosis-deficient MGL1 mediated Ca²⁺-dependent IAV binding but were less sensitive to IAV infection, indicating that direct internalization via MGL1 can result in cellular infection. Together, these studies identify MGL1 as a cell surface glycoprotein that can act as an authentic receptor for both attachment and infectious entry of IAV.     

阴道毛滴虫蛋氨酸裂解酶的基因克隆及重组酶性质分析

为研究重组阴道毛滴虫蛋氨酸裂解酶的活性,从阴道毛滴虫提取RNA,经过RT-PCR克隆蛋氨酸γ-裂解酶基因,与pET-15b质粒连接构建原核表达载体pET-15b-mgl1,并测序。转化宿主菌BL21后进行诱导表达,分离纯化目的蛋白并研究其酶学性质。以L-蛋氨酸、DL-同型半胱氨酸、L-半胱氨酸为底物测定重组酶Km值为0.318、2.14、1.62mmol/L,比活性分别为20.17、318.69、56.96μmol/min/mg protein。MGL最适pH在5.0到6.0之间,在50℃可稳定30min无活性损失。实验结果显示重组酶具有较高的活性和较好的热稳定性,为临床应用研究奠定基础。     

The amino acids involved in the distinct carbohydrate specificities between macrophage galactose-type C-type lectins 1 and 2 (CD301a and b) of mice

Binding specificities of mouse macrophage galactose-type C-type lectin 1 (MGL1/CD301a) and 2 (MGL2/CD301b) toward various oligosaccharides were compared by frontal affinity chromatography. MGL1 preferentially bound oligosaccharides containing Lewis(X) (Le(X)) trisaccharides among 111 oligosaccharides tested, whereas MGL2 preferentially bound globoside Gb4. The important amino acids for the preferential bindings were investigated by pair-wise site-directed mutagenesis at positions 61, 89, 97, 100, 110-113, 115, 124, and 125 in the soluble recombinant carbohydrate recognition domains (CRD) prepared in Escherichia coli and purified with galactose-Sepharose. Mutations of Val, Ala, Thr, and Phe at positions 61, 89, 111 and 125 on MGL1 CRD caused reductions in Le(X) binding. Mutations of MGL2 CRD at Leu, Arg, Arg, and Tyr at positions 61, 89, 115 and 125 were implicated in the preference for beta-GalNAc. Le(X) binding was observed with MGL2 mutants of Arg89Ala and Arg89Ala/Ser111Thr. MGL1 mutants of Ala89Arg and Ala89Arg/Pro115Arg showed beta-GalNAc bindings. Molecular modeling illustrated potential direct molecular interactions of Leu61, Arg89, and His109 in MGL2 CRD with GalNAc.     

The C-type lectin MGL expressed by dendritic cells detects glycan changes on MUC1 in colon carcinoma

The epithelial mucin MUC1 is a high molecular weight membrane glycoprotein frequently overexpressed and aberrantly glycosylated in adenocarcinoma. Mucins normally contain high amounts of O-linked carbohydrate structures that may influence immune reactions to this antigen. During malignant transformation, certain glyco-epitopes of MUC1, such as Tn-antigen, TF-antigen and their sialylated forms become exposed. The role of these glycan structures in tumor biology is unknown, but their presence is known to correlate with poor prognosis in several adenocarcinomas. We analyzed the potency of MUC1 containing Tn-antigens (MUC1-Tn) to target C-type lectins that function as carbohydrate recognition and uptake molecules on dendritic cells (DC). We identified the macrophage galactose type C-type lectin (MGL), expressed by both DC and macrophages, as the receptor for recognition and binding of MUC1-Tn. To validate the occurrence of MGL–MUC1 interactions in situ, we studied the binding of MGL to MUC1 in primary colon carcinoma tissue. Isolation of MUC1 out of colon carcinoma tissue showed strong binding activity to MGL. Interestingly, MGL binding to MUC1 was highly correlated to binding by the lectin Helix pomatia agglutinin (HPA), which is associated with poor prognosis in colorectal cancer. The detection of MGL positive cells in situ at the tumor site together with the modified glycosylation status of MUC1 to target MGL on DC suggests that MGL positive antigen presenting cells may play a role in tumor progression.     

Properties of blocking and non-blocking monoclonal antibodies specific for human macrophage galactose-type C-type lectin (MGL/ClecSF10A/CD301)

Monoclonal antibodies (mAbs) specific for the human macrophage galactose-type calcium-type lectin (MGL) were established. The recombinant extracellular domain of MGL was used to immunize a mouse, and 10 hybridoma clones were obtained. Binding of recombinant MGL to asialo-bovine submaxillary mucin was shown to be blocked by mAbs MLD-1, 4 and 6. Immunoprecipitation of MGL from lysates of COS-1 cells transfected with MGL cDNA (form 6A) was achieved with mAbs MLD-1, 4, 7, 8 and 16. Chimeric recombinant proteins between human MGL and mouse MGL1 were used to determine the location of the epitopes for these mAbs. mAbs MLD-8, 13, 15 and 16 interacted with the amino terminal side of the conserved WVDGTD sequence immediately upstream of QPD, whereas mAbs MLD-7, 12 and 17 interacted with the other side. mAbs MLD-1, 4, and 6 apparently required both sides of this boundary. mAbs MLD-15 and 16 were shown to recognize the protein products of alternatively spliced mRNA 6A/8A and 6C/8A, having deletions at the boundary of exons 7 and 8, in addition to full length and other spliced forms of MGL (6A, 6B and 6C), whereas the other mAbs bound only full length and forms 6A, 6B and 6C.     

Genetic redundancy in yeast: Non-identical products in a polymeric gene system

Summary The -methylglucoside fermenting enzymes produced in response to the two complementing gene pairs (MGL1 MGL2) and (MGL3 MGL2) were purified and certain of their physical properties were compared. Although both enzymes have the same molecular weight, substrate and serological specificities, they differ with respect to their specific activity, Michaelis constant and heat stability. On the basis of these findings we argue that the loci MGL1 and MGL3 are the structural genes responsible for the production of the -methylglucosidases in yeast and that the loci controlling maltase and -methylglucosidase production arose from a common ancestor by gene duplication.     

Distribution and function of monoacylglycerol lipase in the gastrointestinal tract

The endogenous cannabinoid system plays an important role in the regulation of gastrointestinal function in health and disease. Endocannabinoid levels are regulated by catabolic enzymes. Here, we describe the presence and localization of monoacylglycerol lipase (MGL), the major enzyme responsible for the degradation of 2-arachidonoylglycerol. We used molecular, biochemical, immunohistochemical, and functional assays to characterize the distribution and activity of MGL. MGL mRNA was present in rat ileum throughout the wall of the gut. MGL protein was distributed in the muscle and mucosal layers of the ileum and in the duodenum, proximal colon, and distal colon. We observed MGL expression in nerve cell bodies and nerve fibers of the enteric nervous system. There was extensive colocalization of MGL with PGP 9.5 and calretinin-immunoreactive neurons, but not with nitric oxide synthase. MGL was also present in the epithelium and was highly expressed in the small intestine. Enzyme activity levels were highest in the duodenum and decreased along the gut with lowest levels in the distal colon. We observed both soluble and membrane-associated enzyme activities. The MGL inhibitor URB602 significantly inhibited whole gut transit in mice, an action that was abolished in cannabinoid 1 receptor-deficient mice. In conclusion, MGL is localized in the enteric nervous system where endocannabinoids regulate intestinal motility. MGL is highly expressed in the epithelium, where this enzyme may have digestive or other functions yet to be determined.     

The C-type lectin macrophage galactose-type lectin impedes migration of immature APCs

Dendritic cells (DCs) are the most potent APCs of the immune system that seed the peripheral tissues and lymphoid organs. In an immature state, DCs sample their surroundings for incoming pathogens. Upon Ag encounter, DCs mature and migrate to the lymph node to induce adaptive immune responses. The C-type macrophage galactose-type lectin (MGL), expressed in immature DCs, mediates binding to glycoproteins carrying GalNAc moieties. In the present study, we demonstrate that MGL ligands are present on the sinusoidal and lymphatic endothelium of lymph node and thymus, respectively. MGL binding strongly correlated with the expression of the preferred MGL ligand, alpha-GalNAc-containing glycan structures, as visualized by staining with the alpha-GalNAc-specific snail lectin Helix pomatia agglutinin. MGL(+) cells were localized in close proximity of the endothelial structures that express the MGL ligand. Strikingly, instead of inducing migration, MGL mediated retention of human immature DCs, as blockade of MGL interactions enhanced DC trafficking and migration. Thus, MGL(+) DCs are hampered in their migratory responses and only upon maturation, when MGL expression is abolished; these DCs will be released from their MGL-mediated restraints.     

Cyclic changes in endometrial echotexture of cows using a computer-assisted program for the analysis of first- and second-order grey level statistics of B-Mode ultrasound images

The aim of this study was to test the suitability of a computer-assisted echotexture analysis program for analysing first- and second-order grey level statistics of grey levels of B-Mode ultrasound images to examine morphologic changes in the endometrium during oestrous cycle in cows. Four Simmental cows were examined for two consecutive oestrous cycles. Echotexture of the endometrium was assessed by mean grey level (MGL) and homogeneity (HOM) of digitised B-Mode images of the uterine body and both uterine horns. As there were no differences (P>0.05) in MGL and HOM, respectively, between the images of the uterine body and the uterine horns, the mean values of all endometrial images were used for subsequent analyses of MGL and HOM. The factor 'day of oestrous cycle' showed a highly significant (P<0.0001) effect and the factor 'cow' showed a significant (P<0.05) effect on MGL and HOM. No differences (P>0.05) in both echotexture parameters were measured between oestrous cycles within cows. MGL was negatively related to HOM (r=-0.66; P<0.0001). Low MGL and high HOM occurred on Day 0 (=ovulation) and between Days -3 and -1. While MGL was consistently (P>0.05) low between Days -3 and -1, significant changes of HOM with maximum levels on Day -2 (P<0.05) were observed during this time. MGL was consistently (P>0.05) high between Days 4 and 13 while HOM was consistently (P>0.05) low between Days 2 and 13. From Day -3 to Day -1 (r=0.48; P<0.05) plasma oestrogen levels were correlated with HOM, but not with MGL (P<0.05). The results of this study show that changes in endometrial morphology of cows can be measured using a computer-assisted texture analysis program.     

A role for monoglyceride lipase in 2-arachidonoylglycerol inactivation

2-Arachidonoylglycerol (2-AG) is a naturally occurring monoglyceride that activates cannabinoid receptors and meets several key requisites of an endogenous cannabinoid substance. It is present in the brain (where its levels are 170-folds higher than those of anandamide), is produced by neurons in an activity- and calcium-dependent manner, and is rapidly eliminated. The mechanism of 2-AG inactivation is not completely understood, but is thought to involve carrier-mediated transport into cells followed by enzymatic hydrolysis. We examined the possible role of the serine hydrolase, monoglyceride lipase (MGL), in brain 2-AG inactivation. We identified by homology screening a cDNA sequence encoding for a 303-amino acid protein, which conferred MGL activity upon transfection to COS-7 cells. Northern blot and in situ hybridization analyses revealed that MGL mRNA is unevenly present in the rat brain, with highest levels in regions where CB1 cannabinoid receptors are also expressed (hippocampus, cortex, anterior thalamus and cerebellum). Immunohistochemical studies in the hippocampus showed that MGL distribution has striking laminar specificity, suggesting a presynaptic localization of the enzyme. Adenovirus-mediated transfer of MGL cDNA into rat cortical neurons increased the degradation of endogenously produced 2-AG in these cells, whereas no such effect was observed on anandamide degradation. These results indicate that hydrolysis via MGL may be a primary route of 2-AG inactivation in intact neuronal cells.     

Deletion of Monoglyceride Lipase in Astrocytes Attenuates Lipopolysaccharide-induced Neuroinflammation

Monoglyceride lipase (MGL) is required for efficient hydrolysis of the endocannabinoid 2-arachidonoylglyerol (2-AG) in the brain generating arachidonic acid (AA) and glycerol. This metabolic function makes MGL an interesting target for the treatment of neuroinflammation, since 2-AG exhibits anti-inflammatory properties and AA is a precursor for pro-inflammatory prostaglandins. Astrocytes are an important source of AA and 2-AG, and highly express MGL. In the present study, we dissected the distinct contribution of MGL in astrocytes on brain 2-AG and AA metabolism by generating a mouse model with genetic deletion of MGL specifically in astrocytes (MKO^GFAP). MKO^GFAP mice exhibit moderately increased 2-AG and reduced AA levels in brain. Minor accumulation of 2-AG in the brain of MKO^GFAP mice does not cause cannabinoid receptor desensitization as previously observed in mice globally lacking MGL. Importantly, MKO^GFAP mice exhibit reduced brain prostaglandin E2 and pro-inflammatory cytokine levels upon peripheral lipopolysaccharide (LPS) administration. These observations indicate that MGL-mediated degradation of 2-AG in astrocytes provides AA for prostaglandin synthesis promoting LPS-induced neuroinflammation. The beneficial effect of astrocyte-specific MGL-deficiency is not fully abrogated by the inverse cannabinoid receptor 1 agonist SR141716 (Rimonabant) suggesting that the anti-inflammatory effects are rather caused by reduced prostaglandin synthesis than by activation of cannabinoid receptors. In conclusion, our data demonstrate that MGL in astrocytes is an important regulator of 2-AG levels, AA availability, and neuroinflammation.     

Kinetic characterization of methionine gamma-lyases from the enteric protozoan parasite Entamoeba histolytica against physiological substrates and trifluoromethionine, a promising lead compound against amoebiasis

Methionine gamma-lyase (MGL) (EC 4.4.1.11), which is present in certain lineages of bacteria, plants, and protozoa but missing in mammals, catalyzes the single-step degradation of sulfur-containing amino acids (SAAs) to alpha-keto acids, ammonia, and thiol compounds. In contrast to other organisms possessing MGL, anaerobic parasitic protists, namely Entamoeba histolytica and Trichomonas vaginalis, harbor a pair of MGL isozymes. The enteric protozoon En. histolytica shows various unique aspects in its metabolism, particularly degradation of SAAs. Trifluoromethionine (TFM), a halogenated analog of Met, has been exploited as a therapeutic agent against cancer as well as against infections by protozoan organisms and periodontal bacteria. However, its mechanism of action remains poorly understood. In addition, the physiological significance of the presence of two MGL isozymes in these protists remains unclear. In this study, we compared kinetic parameters of the wild-type and mutants, engineered by site-directed mutagenesis, of the two MGL isotypes from En. histolytica (EhMGL1 and EhMGL2) for various potential substrates and TFM. Intracellular concentrations of l-Met and l-Cys suggested that these SAAs are predominantly metabolized by EhMGL1, not by EhMGL2. It is unlikely that O-acetyl-l-serine is decomposed by EhMGLs, given the kinetic parameters of cysteine synthase reported previously. Comparison of the wild-type and mutants revealed that the contributions of several amino acids implicated in catalysis differ between the two isozymes, and that the degradation of TFM is less sensitive to alterations of these residues than is the degradation of physiological substrates. These results support the use of TFM to target MGL.     

Conformational Transition Pathway in the Inhibitor Binding Process of Human Monoacylglycerol Lipase

Human monoacylglycerol lipase (MGL) catalyzes the hydrolysis of 2-arachidonoylglycerol to arachidonic and glycerol, which plays a pivotal role in the normal biological processes of brain. Co-crystal structure of the MGL in complex with its inhibitor, compound 1, shows that the helix α4 undergoes large-scale conformational changes in response to the compound 1 binding compared to the apo MGL. However, the detailed conformational transition pathway of the helix α4 in the inhibitor binding process of MGL has remained unclear. Here, conventional molecular dynamics (MD) and nudged elastic band (NEB) simulations were performed to explore the conformational transition pathway of the helix α4. Conventional MD simulations unveiled that the compound 1 induced the closed conformation of the active site of MGL, reduced the conformational flexibility of the helix α4, and elicited the large-scale conformational rearrangement of the helix α4, leading to the complete folding of the helix α4. Moreover, NEB simulations revealed that the conformational transition pathway of helix α4 underwent an almost 180° counter-clockwise rotation of the helix α4. Our computational results advance the structural and mechanistic understanding of the inhibitory mechanism.     

Distribution and Function of Macrophage Galactose-type C-type Lectin 2 (MGL2/CD301b): EFFICIENT UPTAKE AND PRESENTATION OF GLYCOSYLATED ANTIGENS BY DENDRITIC CELLS*

Dendritic cells (DCs) express cell surface lectins that are potentially involved in the recognition, uptake, and presentation of glycosylated foreign substances. A unique calcium-type (C-type) lectin, the macrophage galactose (Gal)-type C-type lectin (MGL/CD301) expressed on DCs, is thought to participate in the recognition of molecules from both altered self and pathogens due to its monosaccharide specificity for Gal and N-acetylgalactosamine (GalNAc). Although mice have two MGL genes, Mgl1 and Mgl2, their distinct roles have not been previously explored. The present report characterizes the properties of MGL2 by examining its distribution and its role in antigen presentation by DCs. We generated an MGL2-specific monoclonal antibody and examined MGL2 expression in tissues by immunohistochemistry and in isolated cells by flow cytometry. The cells reactive with this antibody were shown to be a portion of MGL1-expressing cells, mostly conventional DCs. Internalization of soluble polyacrylamide polymers (PAA) with α-GalNAc residues (GalNAc-PAA) by bone marrow-derived DCs (BM-DCs) was mediated by MGL2, as revealed by a comparison of Mgl1^−/− and Mgl2^−/− BM-DCs with wild-type BM-DCs. Biotinylated GalNAc-PAA conjugated to streptavidin (SAv) was more efficiently presented to SAv-primed T cells by BM-DCs than β-N-acetylglucosamine-PAA conjugated to SAv or SAv alone as shown by thymidine uptake and cytokine production. This is the first report that demonstrates the involvement of GalNAc residues in antigen uptake and presentation by DCs that lead to CD4⁺ T cell activation.