Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis:

Summary Approximately 250 phytohemagglutinin (PHA)-stimulated peripheral blood lymphocyte polypeptides from three unrelated healthy males were compared by high-resolution two-dimensional gel electrophoresis and double-label autoradiography. Comparisons by all possible pairwise combinations of [¹⁴C]leucine-labeled proteins from an individual and [³H]leucine-labeled proteins from another revealed that only three polypeptides differed qualitatively among the three individuals. The degree of variation in lymphocyte polypeptides between different individuals was similar to that in fibroblast polypeptides reported previously. Among the three variant polypeptides, two polypeptides with mol.wt. 64,000 and mol. wt. 37,000 coexisted with a polypeptide with the same molecular weight, and they showed the behavior expected of two allelic gene products separated in the isoelectric focusing dimension by charge differences. Analysis of [¹⁴C]leucine labeled peripheral blood lymphocyte proteints, from the parents of each individual, by two-dimensional gel electrophoresis indicated that the variant polypeptides with mol. wt. 64,000 and mol. wt. 37,000 in the propositus were inherited from one of his parents. The data indicate that genetic analysis of PHA-stimulated peripheral blood lymphocyte proteins is feasible by high-resolution two-dimensional gel electrophoresis in combination with double-label autoradiography and pedigree analysis.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis

Summary We describe a genetic polymorphism of cytosol polypeptide with mol. wt. of 38,000 detected in phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes by two-dimensional gel electrophoresis. Three different electrophoretic phenotypes (type 1-1, 2-1, 2-2) of the polypeptide have been identified in a Japanese population. Family and population studies indicate that three phenotypes are determined by two common alleles at a single autosomal locus. Since the polypeptide is mainly present in cytosol of cells, we propose that the polypeptide be temporarily designated as cytosol polypeptide with mol. wt. of 38,000 (CP 38) and that the gene for CP 38 be designated as CP 38. The gene frequencies of two common alleles (CP 38 ¹ and CP 38 ²) are 0.899 and 0.101, respectively, in a Japanese population. The data on gel filtration of cytosol proteins on a Sephadex G-100 column suggest that CP 38 exists as a dimer in the cytosol. CP 38 was observed in the wide range of different cells, including B-lymphoblastoid cells, adult skin fibroblasts, HeLa cells, and erythrocytes. In 11 out of 72 individuals, the phenotypes of CP 38 were different from those of adenosine deaminase which is similar to CP 38 in subunit size, cell distribution, and allele frequencies. These data indicate that CP 38 is a new polymorphic polypeptide encoded by an autosomal locus.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis:

Summary Three different electrophoretic types (1-1, 2-1 and 2-2) of a human cellular polypeptide with molecular weight of 31000 have been identified by the analysis of PHA-stimulated peripheral blood lymphocyte proteins using high resolution two-dimensional gel electrophoresis. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The 31k polypeptide appears to be present as a monomer in the cytosol in a wide range of different cell types, including permanent lymphoblastoid cell lines, fibroblasts and HeLa cells. In an individual with the 31k polypeptide type 2-2, the phenotypes of adenosine deaminase and uridine monophosphate kinase were both type 1. These data indicate that the 31K polypeptide is a new polymorphic protein encoded by a new autosomal locus. It is proposed that the polypeptide and its locus be temporarily designated cytosol 31k polypeptide (C31k polypeptide) and C31P, respectively. In a Japanese population, the gene frequencies of C31P ¹ and C31P ² were 0.940 and 0.060, respectively. The C31k polypeptide type 2-2 appears to be a molecular weight variant as well as a charge variant.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis

Summary We describe a genetic polymorphism of cytosol polypeptide with mol.wt. of 20,000 detected in lymphocytes the arythrocytes by two-dimensional gel electrophoresis. Three different electrophoretic phenotypes (type 1-1, 2-1, and 2-2) of the polypeptide have been identified in a Japanese population. Family studies indicate that the phenotypes are determined by two common alleles at a single autosomal locus. The polypeptide is present in the cytosol of various kinds of cells and is abundant in erythrocytes. The data on a gel filtration of the erythrocyte cytosol proteins on a Sephadex G-100 column suggest that the polypeptide exists as a dimer in cells. In nine out of 79 individuals, the phenotypes of the polypeptide were different from those of glyoxalase 1 (GLO1) which has similar properties in subunit size, cell distribution, and allele frequencies. These date indicate that the polypeptide with mol. wt. of 20,000 is a new polymorphic cellular polypeptide. We propose that the polypeptide be temporarily designated as cytosol polypeptide with mol. wt. of 20,000 (CP20) and that the gene for CP20 be designated as CP20. The gene frequencies of two common alleles (CP20 ¹ and CP20 ²) are 0.955 and 0.045, respectively, in a Japanese population.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: 2. Genetic polymorphism of lymphocyte cytosol 64K polypeptide

Summary We describe a genetic polymorphism of human lymphocyte cytosol major polypeptide with mol. wt. 64,000, detected in peripheral blood lymphocytes by high resolution two-dimensional electrophoresis. Three different electrophoretic types (1-1, 2-1, 2-2) of the polypeptide have been identified. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The polypeptide occurs in the cytosol and is predominent in peripheral blood lymphocytes, B-lymphoblastoid cells, T-lymphoblastoid cells, lymph node, and spleen. The polypeptide has not been detected in HeLa cells, fibroblasts, erythrocytes, serum, and cerebrum. Traces of the polypeptide exist in liver, kidney, and skeletal muscle. It is proposed that the polypeptide and its locus be temporarily designated lymphocyte cytosol 64K polypeptide (LC64K polypeptide) andLC64P, respectively. In a Japanese population, the gene frequencies ofLC64P ¹ andLC64P ² were 0.936 and 0.064, respectively. The data suggest thatLC64P is a new locus, product of which shows genetic polymorphism and is associated with the function and/or the structure of lymphocytes.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: 4. Genetic polymorphism of cytosol 100k polypeptide

Summary We describe a genetic polymorphism of a human cellular polypeptide with mol. wt. 100,000, detected in peripheral blood lymphocytes by high resolution two-dimensional electrophoresis. Three different electrophoretic types (1-1, 2-1, and 2-2) of the polypeptide have been identified. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The polypeptide occurs in the cytosol and is one of the abundant polypeptides of B-lymphoblastoid cells, T-lymphoblastoid cells, fibroblasts, and HeLa cells. The data indicate that the cytosol polypeptide with mol.wt. 100,000 shows a genetic polymorphism determined by aew autosomal locus. It is proposed that the polypeptide and its locus be temporarily designated cytosol 100k polypeptide (C100k polypeptide) and C100P, respectively. In a Japanese population, the gene frequencies of C100P ¹ and C100P ² were 0.907 and 0.093, respectively.     

Identification of genetic variants in erythrocyte lysate by two-dimensional gel electrophoresis.

Two-dimensional gel electrophoresis followed by silver-staining has been employed to study 27 red cell lysates for genetic variation. Forty-six polypeptides selected without respect to variability were considered suitable for scoring. Only 23 of the total of 1,242 polypeptides could not be scored unambiguously. Of the remaining 1,219 polypeptides, 38 exhibited the combination of a normal and a variant polypeptide. All variants were present in either the father or the mother of the subjects. The observed index of heterozygosity was 3.1% +/- 0.5%.     

Genetic variants detected among 106 lymphocyte polypeptides observed in two-dimensional gels.

Peripheral blood lymphocytes from 40 children have been examined for genetic variation in their protein constituents by two-dimensional polyacrylamide gel electrophoresis. One hundred six polypeptides chosen without respect to genetic variability were scored in gels from the 40 children. For each child, gels from both parents were also examined to substantiate the genetic basis of variants observed. Of the total of 4,240 polypeptides, 23 could not be scored unambiguously. Fourteen of the polypeptides showed genetic variants in one or more of the children. One hundred twenty-nine of 4,217 polypeptides scored exhibited the combination of a normal and a variant polypeptide. All variants were present in at least one of the parents of the subject. The index of heterozygosity observed (3.05% +/- .23%) indicates substantial genetic variation in cellular protein constituents.     

Rapid two-dimensional analysis of proteins by ultra-thin layer gel electrophoresis

Identification of qualitative and/or quantitative protein expression differences as well as characterization of specific cell proteomes would further advance molecular cell biology research. Today, one of the most commonly used tools for proteome analysis is two-dimensional gel electrophoresis. Although this technology is informative, it is extremely cumbersome, time-consuming and lacks automation and proper reproducibility. In this paper, we propose an automated separation/detection system capable of rapid two-dimensional analysis of proteins by ultra-thin layer gel electrophoresis with real time imaging of the separated components, using fiber optics based laser induced fluorescence technology. The approach is based on electric field mediated separation in capillary dimensions, along with noncovalent, "in migratio" fluorescent staining methodology. The advantage of the technology discussed over existing techniques is its simplicity, speed and good detection sensitivity.     

Preparation of membrane proteins for analysis by two-dimensional gel electrophoresis

In order to separate hydrophobic membrane proteins, we have developed a novel two-dimensional electrophoresis system. For the iso-electric focusing, agarose was used as a supporting matrix and n-dodecyl-beta-D-maltopyranoside was used as a surfactant. In combination with a previously developed Tris/MES electrophoresis system in the second dimension, distinct spots were reproducibly detected from hydrophobic membrane proteins whose grand average hydropathicity (GRAVY) exceed 0.3. In contrast to the immobilized pH gradient system, c-type heme was also visualized in this system.     

The effect of estrogen on the incorporation of 3H-thymidine by PHA-stimulated human peripheral blood lymphocytes

The effect of estrogen on the incorporation of tritiated thymidine by phytohemagglutinin (PHA)-stimulated human peripheral blood lymphocytes was evaluated in 15 adult males. Varying concentrations of diethylstilbestrol diphosphate (DEP-S) were added to peripheral blood lymphocytes with and without PHA to study the effects of estrogen on blastogenesis. Maximum suppression of blastogenesis occurred after the addition of 500 mcg/ml culture of DEP-S. The absence and presence of DEP-S 500 mcg/ml culture resulted in a 52% reduction in lymphocytic reactivity (p.002). It was concluded that this reduction or suppression of lymphocytic blastogenesis in the presence of estrogen suggests that the palliative effects of estrogenic therapy in treating patients with hormone-dependent tumors may be countered by its adverse effect on the host's immunologic responsiveness to malignancy.     

Analysis of lymphocyte proteins from New Zealand black mice by two-dimensional gel electrophoresis

Splenic lymphocyte proteins from New Zealand Black (NZB) mice, which spontaneously develop autoimmune disease, and several control strains were analyzed by two-dimensional polyacrylamide gel electrophoresis. A number of strain- and age-related differences were observed, among which was the persistently elevated synthesis of two peptides, 12.5 KD and 10.5 KD, by spleen cells from older NZB mice. Although synthesis of these peptides was moderately high in young NZB and control mice, it diminished with age in control mice. These proteins were found in the cytoplasm and were not expressed on the plasma membrane nor secreted into the medium. Production of these proteins was restricted to B and null cells; T cells did not synthesize these peptides. These proteins appear to be indicators of disease activity, because their increased synthesis was associated with lymphocyte subset alterations associated with the onset of overt autoimmune disease in NZB mice.     

Analysis of normal and neoplastic lymphocyte surface-labeled proteins by two-dimensional polyacrylamide gel electrophoresis

Normal and neoplastic murine and human lymphocytes were surface-labeled by lacto-peroxidase-catalyzed radioiodination, and the cell lysates were subjected to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) analyses, combining isoelectric focusing in the first dimension and sodium dodecyl sulfate-PAGE (SDS-PAGE) in the second dimension. 2D-PAGE autoradiogram patterns were reproducible and reflected differences in cell types. A string of spots with a Mr of 100K was tentatively identified as a new T-cell marker (Tp100) which was present in all murine and human T cells examined including human T lymphomas. Murine and human B cells displayed markers characteristic to B cells of each species with some similarities between them. Human lymphomas and murine cell lines showed markers which were absent or only weakly visible in normal cells. Thus, 2D-PAGE analysis of lymphocyte surface proteins proved to be a method useful for searching for various markers.     

High resolution two-dimensional gel electrophoresis of human erythrocyte membrane proteins.

Three different two-dimensional (2-D) gel electrophoretic techniques have been modified to provide high resolution of human erythrocyte membrane proteins. The resulting gels were referenced to the established one-dimensional (1-D) sodium dodecylsulfate (SDS) gel electrophoretic profile, and the effects of endogenous proteolysis and cytosolic contamination were studied. It is concluded that in vitro proteolysis and cytosolic contamination do not contribute significantly to the patterns observed on the 2-D gels, under the conditions used for erythrocyte ghost preparation. The procedures require only small quantities of blood; as many as twenty 2-D gel profiles can be obtained from 5 ml of blood. The combination of nonequilibrium isoelectric focusing (IEF) in the first dimension, SDS electrophoresis in the second dimension, and very sensitive silver staining techniques resolves more than 250 individual protein spots. This appears to be the most useful single procedure for the analysis of red cell membrane proteins. Membrane protein profiles from patients with Duchenne muscular dystrophy, Wernicke-Korsakoff syndrome, and acanthocytosis with degeneration of the basal ganglia were compared with normal controls. The patterns for Duchenne muscular dystrophy and Wernicke-Korsakoff syndrome were not different from normal patterns. The pattern for the patient with acanthocytosis and degeneration of the basal ganglia consistently showed a high level for one protein in the 100,000 mol. wt. range.     

Analyses of genetic variants of l-glycerol-3-phosphate dehydrogenase in Drosophila melanogaster by two-dimensional gel electrophoresis and immunoelectrophoresis

A protein spot corresponding to l-glycerol-3-phosphate dehydrogenase (α-GPDH, E.C. 1.1.1.8, NAD⁺ oxidoreductase) has been identified on a two-dimensional gel (isoelectric focusing-SDS gel) containing up to 150 stained protein spots from a crude Drosophila homogenate. Preliminary identification of the α-GPDH spot was made by including a suitable amount of purified Drosophila α-GPDH in crude fly homogenates prior to electrophoresis and observing an intensity enhancement of the corresponding protein spot on the gels. When three purified electrophoretic variants (slow, fast, and ultrafast) were mixed and analyzed by two-dimensional gel electrophoresis, horizontal displacements of the three protein spots were observed. Immunoprecipitation of the enzyme prior to electrophoresis and gene mapping further confirmed the identity of the α-GPDH protein spot. The α-GPDH spot can also be detected by autoradiography of a two-dimensional gel from a single fly extract, where it has been estimated to constitute 0.5–1% of the total soluble protein. Mutants which express no apparent α-GPDH activity were analyzed by two-dimensional gels and immunoelectrophoresis in an attempt to identify and characterize the inactive proteins. It is suggested that these techniques provide a powerful tool for the analysis of CRM⁺-null activity mutants of a specific gene-enzyme system.     

Yeast plasma membrane ghosts. An analysis of proteins by two-dimensional gel electrophoresis

We have examined yeast cell ghost preparations to assess their value in obtaining plasma membrane proteins. Ghosts prepared by two methods involving stabilization of spheroplast envelopes had similar protein patterns by two-dimensional gel electrophoresis, and approximately 200 proteins were resolved. Spheroplasts were lactoperoxidase iodinated, and recovery of label in ghost preparations was greater than 60%. Spheroplasts appeared to be impermeable to the lactoperoxidase reagents as judged by an examination of two-dimensional gel electrophoretic patterns of ghost proteins that had been iodinated in spheroplasts or in unsealed ghosts. Spheroplasts were also impermeable to pronase proteases. Surface iodination and surface proteolysis allowed us to identify exposed ghost proteins; the major ghost glycoprotein was exposed in spheroplasts.Two-dimensional patterns of ghost proteins were not heavily contaminated (?25% of all proteins) by proteins present in soluble or promitochondrial fractions, and estimates of surface label and total cell protein recovery suggested that the ghost fraction represents a cell envelope enrichment of 8–10 fold over whole cells.Resolution of ghost proteins by two-dimensional gel electrophoresis appears to be a powerful aid toward identifying membrane proteins.     

Characterisation of human and murine snRNP proteins by two-dimensional gel electrophoresis and phosphopeptide analysis of U1-specific 70K protein variants.

The proteins of the major human snRNPs U1, U2, U4/U6 and U5 were characterised by two-dimensional electrophoresis, with isoelectric focussing in the first dimension and SDS-polyacrylamide gel electrophoresis in the second. With the exception of protein F, which exhibits an acidic pl value (pl = 3.3), the snRNP proteins are basic. Post-translational modification was found among the proteins associated specifically with the U1 and U2 particles. The most complex modification pattern was observed for the U1-specific 70K protein. This was found in at least 13 isoelectric variants, with pl values ranging from 6.7 to 8.7; these variants differed also in molecular weight. All of the 70K variants are phosphorylated in the cell. Thin-layer analysis of their tryptic phosphopeptides revealed that the 70K variants have four major phosphopeptides in common, in addition to which at least four additional serine residues are phosphorylated to different extents. The comparative phosphopeptide analysis shows that differential phosphorylation alone is not sufficient to explain the occurrence of the many isoelectric variants of 70K, so that the final charge of the 70K variants is determined both by phosphorylation and by other, as yet unidentified posttranslational modifications. By two-dimensional separation of snRNP proteins obtained from mouse Ehrlich ascites tumour cells, it was shown that the pattern of pl values of the mouse proteins was almost identical with the corresponding pattern for human proteins. Even the complex modification patterns of the 70K protein are identical in mouse and man, indicating that the presence in the cell of so many variants of this protein may have functional importance. The major difference between murine and human snRNP proteins is the absence of protein B' from mouse snRNPs. This suggests that the homologous protein B may be able to carry out the task of protein B'.     

Yeast plasma membrane ghosts. An analysis of proteins by two-dimensional gel electrophoresis.

We have examined yeast cell ghost preparations to assess their value in obtaining plasma membrane proteins. Ghosts prepared by two methods involving stabilization of spheroplast envelopes had similar protein patterns by two-dimensional gel electrophoresis, and approximately 200 proteins were resolved. Spheroplasts were lactoperoxidase iodinated, and recovery of label in ghost preparations was greater than 60%. Spheroplasts appeared to be impermeable to the lactoperoxidase reagents as judged by an examination of two-dimensional gel electrophoretic patterns of ghost proteins that had been iodinated in spheroplasts or in unsealed ghosts. Spheroplasts were also impermeable to pronase proteases. Surface iodination and surface proteolysis allowed us to identify exposed ghost proteins; the major ghost glycoprotein was exposed in spheroplasts. Two-dimensional patterns of ghost proteins were not heavily contaminated (less than or equal to 25% of all proteins) by proteins present in soluble or promitochondrial fractions, and estimates of surface label and total cell protein recovery suggested that the ghost fraction represents a cell envelope enrichment of 8--10 fold over whole cells. Resolution of ghost proteins by two-dimensional gel electrophoresis appears to be a powerful aid toward identifying membrane proteins.     

Genetic polymorphism in normal human fibroblasts as analyzed by two-dimensional polyacrylamide gel electrophoresis.

Two dimensional gel electrophoresis has been used to measure the degree of genetic polymorphism among the proteins of normal human fibroblasts. Autoradiographic analysis of the gel protein profiles from radioactively labeled cells allowed comparison of as many as 300 discrete polypeptides at a time. In addition, a newly developed technique for double label autoradiography was used to increase the sensitivity of the system for detection of small differences in the protein profiles of different cell lines. Only about 1.2% of the proteins of different cell lines were found to differ in their electrophoretic mobility. This corresponds to an average heterozygosity of approximately 0.6%. Previous studies of genetic polymorphism using different methods of one-dimensional electrophoretic analysis have estimated the average heterozygosity of the human population at about 6.7%. Detailed mathematical analysis shows the variation of the observed from the expected number of differences to be statistically highly significant. While the reasons for this difference are not clear, the observation of low levels of genetic polymorphism on two-dimensional gels should enhance the usefulness of this technique for detection of altered proteins in inherited disease.     

Solubilization of plant membrane proteins for analysis by two-dimensional gel electrophoresis

A plasma membrane-enriched fraction prepared from barley roots was analyzed by two-dimensional gel electrophoresis. Four methods of sample solubilization were assessed on silver stained gels. When membranes were solubilized with 2% sodium dodecyl sulfate followed by addition of Nonidet P-40, gels had high background staining and few proteins because of incomplete solubilization. Gels of membranes solubilized in urea and Nonidet P-40 had a greater number of proteins but proteins with molecular weights greater than 85,000 were absent and proteins with low molecular weights were diffuse. High molecular weight proteins were present in gels of membranes solubilized in 4% sodium dodecyl sulfate followed by acetone precipitation but background staining and streaking remained a problem. Gels of the best quality were obtained when membrane proteins were extracted with phenol and precipitated with ammonium acetate in methanol; background staining and streaking were diminished and proteins were clearly resolved. This method makes possible the resolution required for meaningful qualitative and quantitative comparisons of protein patterns on two-dimensional gels of plant membrane proteins.