The role of the cysteine-rich region of the β2 integrin subunit in the leukocyte function-associated antigen-1 (LFA-1, αLβ2, CD11a/CD18) heterodimer formation and ligand binding

The cysteine-rich region (CRR) of the β2 integrin subunit was replaced by that of β1 to give the chimera β2NV1. β2NV1 can combine with αL to form a variant leukocyte-function-associated antigen (LFA)-1 on COS cell surface, suggesting that the specificity of the β2 interaction with αL does not lie in the CRR. Unlike those expressing wild-type LFA-1, COS cells expressing αLβ2NV1 are constitutively active in intercellular adhesion molecule (ICAM)-1 adhesion. These results suggest that activation of LFA-1 involves the release of an intramolecular constraint, which is maintained, in part, by the authentic β2 CRR.     

The primary structure of the beta-subunit of the cell surface adhesion glycoproteins LFA-1, CR3 and p150,95 and its relationship to the fibronectin receptor.

The lymphocyte-function-associated antigen-1 (LFA-1), the complement receptor type 3 (CR3) and the antigen p150,95 are cell-surface glycoproteins. They are heterodimeric complexes, each containing a unique alpha-subunit noncovalently associated with a common beta-subunit. We have purified the beta-subunit from human spleen and obtained limited peptide sequences. What appears to be the complete primary structure for the fully processed beta-subunit was obtained by cDNA sequencing of clones from a phorbol ester (PMA) stimulated U937 cDNA library. There are five possible glycosylation sites and a transmembrane segment. The sequence contains a high level of cysteine (7.6%), with 24 of the 57 cysteine residues being found in three repeating units each with eight residues. The entire primary structure has 47% identity to a subunit of a fibronectin binding protein from chicken fibroblasts. It seems that LFA-1, CR3 and p150,95 antigens may belong to an extended family of cell surface molecules including the fibronectin binding protein.     

The human preproapolipoprotein C-II gene. Complete nucleic acid sequence and genomic organization

The complete nucleic acid sequence of human preproapolipoprotein (apo) C-II has been determined from 2 apoC-II clones isolated from 2 different human genomic DNA libraries. The cloned fragments were approx. 14 and 18 kb long, and sequence analysis established that the apoC-II gene consists of 3338 nucleotides containing 3 intervening sequences of 2391, 167, and 298 bases. The first intron is located within the 5'-untranslated region of apoC-II and contains 4 Alu type sequences. The second intron interrupts the codon specifying amino acid - 11 of the apoC-II signal peptide. The last intron, which contains a 38 bp sequence which is repeated 6 times, interrupts the codon specifying for amino acid +44 of the mature apolipoprotein.     

Reduction in the free indole-3-acetic acid levels in Alaska pea toy the gibberellin biosynthesis inhibitor uniconazol

The gibberellin biosynthesis inhibitor uniconazol reduces both the elongation and indole-3-acetic acid content of growing Pisum sativum cv. Alaska intemodes. Both internode growth and indole-3-acetic acid content in uniconazol-treated plants can be elevated by gibberellin A3 treatment. The lengths of the growing intemodes are directly related to the indole-3-acetic acid contents.     

Genetic linkage of Beckwith-Wiedemann syndrome to 11p15.

Beckwith-Wiedemann syndrome (BWS), characterized by multiorgan developmental abnormalities and predisposition to cancer, usually occurs sporadically, but small apparently dominant pedigrees have been described. Since rare patients show varying karyotypic abnormalities on the short arm of chromosome 11, it has been suggested that BWS may be related to the Wilms tumor gene on 11p13 or, alternatively, to growth factor genes on 11p15. We performed genetic linkage analysis on two BWS kindreds, using RFLPs for loci on 11p. BWS was linked to the insulin gene (11p15.5), with an overall maximum lod score of 3.60 (recombination fraction = .00). Linkage to D11S16 (11p13) could be excluded for recombination fractions less than or equal to .03. These results suggest that BWS defines a tumor-predisposition gene on 11p15.     

Identification and characterization of a novel postlarval hemolymph protein from Manduca sexta

The identification, purification and characterization of a new postlarval specific hemolymph protein from Manduca sexta is described. Incorporation of [³⁵S]methionine into Manduca sexta hemolymph proteins in vivo was investigated as a function of development. A major protein band of M_r ≈ 50,000 was highly labeled during the prepupal and adult stage but not in feeding larvae. This postlarval protein (PLP) was isolated from adult male hemolymph and its chemical and immunological properties determined. PLP is a basic protein (pI ～8.6). Electrophoresis under denaturing conditions reveals a subunit M_r ≈ 50,000 while the native protein has an apparent M_r ～ 85,000 by gel permeation chromatography. Anti-PLP serum recognized PLP but not other hemolymph proteins on immunoblots. In vitro translation of fat body mRNA followed by immunoprecipitation revealed that fat body is the site of PLP synthesis. Quantitation of PLP levels in hemolymph throughout development was performed and suggests PLP may play a role in adult development of M. sexta.     

Lipopolysaccharide-induced NF-kappa B activation in mouse 70Z/3 pre-B lymphocytes is inhibited by mevinolin and 5''-methylthioadenosine: roles of protein isoprenylation and carboxyl methylation reactions.

We show that both the lipopolysaccharide (LPS)-induced activation of NF-kappa DNA binding and kappa gene expression are blocked by treating murine pre-B lymphocyte 70Z/3 cells with 5'-methylthioadenosine (MTA), an inhibitor of several S-adenosylmethionine-dependent methylation reactions. We further show that the LPS-induced incorporation of radioactivity from [methyl-3H]methionine into methyl ester-like linkages on a group of membrane polypeptides is also inhibited by MTA treatment, suggesting the involvement of protein methylation reactions in the LPS signal transduction pathway. We also find that NF-kappa B and kappa gene activation in LPS-treated 70Z/3 cells is blocked by mevinolin, an inhibitor that prevents protein isoprenylation. Interestingly, mevinolin-treated cells also exhibited a marked reduction in the methylation of membrane proteins. Neither MTA nor mevinolin significantly inhibited NF-kappa B activation by phorbol myristate acetate, suggesting that these agents act early in signal transduction. These results provide the first evidence that carboxyl methylated and/or isoprenylated proteins play an essential role in the LPS-signaling pathway.