In addition to their well defined role in presentation of processed antigen on the cell surface, class II molecules are able to transduce signals into the cell after binding of ligands. The cytoplasmic regions of class II molecules might function as docking sites for as yet unidentified proteins that are components of this signalling pathway. Here we report on two putative HLA class II associated proteins (PHAPI and PHAPII) which have been purified from the cytosolic fraction of the human lymphoblastoid B-cell line H2LCL using an affinity matrix composed of the synthetic biotinylated cytoplasmic region of the DR2 alpha chain immobilized on avidin agarose. The sequence obtained for PHAPI revealed a novel primary structure with a leucine/isoleucine rich N-terminal region. Protein data and the cDNA sequence obtained for PHAPII agree with the cDNA sequence of SET that has been described recently. Both PHAPI and PHAPII have an extended highly acidic C-terminal region. Based on their primary structure we speculate that PHAPI and PHAPII are involved in the generation of intracellular signalling events that lead to regulation of transcriptional activity after binding of a ligand to HLA class II molecules.
Here we report the complete amino-acid sequence of the anti-o;(2-8)polysialic acid antibody mAb735 light chain. The sequence was determined after digestion of the reduced and carboxymethylated L-chain with trypsin, SV-8 proteinase, and Asp-Nproteinase, isolation of the generated peptides by RP-HPLC and characterization of these fragments by sequence analysis, amino-acid analysis and/or plasma desorption mass spectrometry. According to Kabat et al. the variable region belongs to the -subgroup, whilst according to Hum et al. it belongs to theV x -!B subgroup. With the exception of proline at position 46, the sequence from position 1 to 95 is identical to the translated DNA sequence of a V^-germline gene segment previously reported.
Die Primärstruktur des murinen monoklonalen IgG2a Antikörpers mAb735 gegen a(2-8) Polysialinsäure 1) Aminosäuresequenz der leichten (L-) Kette, -Isotyp
The complete amino acid sequence of the Fd' region including the VH part, the CHI domain, and the hinge segment of the biologically relevant monoclonal mouse anti-a(2-8) polysialic acid antibody mAb735 is presented. The reduced and carboxymethylated Η-chain was digested with trypsin and cyanogen bromide. For subfragmentation selected peptides were cleaved with thermolysin and endoproteinase Asp-N. The generated peptides were isolated by RP-HPLC and characterized by sequence analysis, plasma desorption mass spectrometry (PDMS), and amino acid analysis.The N-terminal sequence was determined after enzymatic deprotection with pyroglutamate aminopeptidase. According to Kabat et al. the variable region of the Η-chain belongs to the subgroup II. Sequence data from the constant region indicate that m Ab735 represents the γ 2a isotype.
The monoclonal mouse IgG2a antibody mAb735 obtained from an autoimmune NZB mouse immunized with live group B meningococci was purified from ascitic fluid. After reduction and carboxymethylation the H chain was digested with trypsin or cyanogen bromide, and peptides isolated by reversed-phase high-performance liquid chromatography were characterized by automated sequence analysis and plasma desorption mass spectrometry either directly or after subfragmentation with endoproteinase Asp-N and c~-chymotrypsin, respectively. Along with previous reports on the L chain (Vaesen et al. 1991) and the F(ab')2 region sequences (Klebert et al. 1993) the H chain sequence reported here completes the primary structure of mAb735. It was determined as the basis for the X-ray structure elucidation which is in progress.The H chain represents the product of the e allele of the Ighl locus, since alloantisera characterize the NZB mouse to express this allele (Green 1989). As in other y2a chains, there is a complex type carbohydrate moiety attached to asparagine in position 314 (Kabat numbering; Kabat et al. 1991). This is heterogeneous with respect to a terminal hexose (fucose or galactose). At the C terminus the usually DNA-encoded lysine is missing, presumably due to a carboxypeptidase activity. In Figure 1 the constant region of the y2a e chain is compared with those of other y2a chains. There are two substitutions to y2a a, one substitution to MAI y2a, but a high level of sequence variation to y2ab and MAI y2c sequences.The amino acid exchanges between y2a a, y2a e, and MAI y2a sequences are restricted to the CH2 region of each The nucleotide sequence data reported in this paper have been submitted to the MIPSX nucleotide sequence database and have been assigned the accession number $40295
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