title: G6b, a novel immunoglobulin superfamily member encoded in the human major histocompatibility complex, interacts with SHP-1 and SHP-2.
abstract: The G6b gene, located in the class III region of the human major histocompatibility complex, has been suggested to encode a putative receptor of the immunoglobulin superfamily. Genomic sequence information was used as a starting point to clone the corresponding cDNA. Reverse transcriptase polymerase chain reaction showed that expression of the gene is restricted to certain hematopoietic cell lines including K562, Molt 4, and Jurkat. Several splice variants were detected, varying only in their C-terminal parts. One of the potential membrane-bound isoforms contained two immunoreceptor tyrosine-based inhibitory motifs in its cytoplasmic tail. Four of the isoforms were expressed as epitope-tagged proteins in the cell lines K562 and COS-7. The two splice isoforms lacking the hydrophobic transmembrane segment were secreted from the cell. Glycosidase treatment of the four recombinant proteins provided evidence for N- and O-glycosylation. Immunofluorescence studies indicated that the spliced isoforms having a transmembrane segment were directed to the cell membrane. The G6b isoform containing two immunoreceptor tyrosine-based inhibitory motifs in its cytoplasmic tail was found to be phosphorylated on tyrosine residues after pervanadate treatment of cells and, subsequently, interacts with the SH2-containing protein-tyrosine phosphatases SHP-1 and SHP-2. Mutagenesis studies showed that phosphorylation of tyrosine 211 is critical for the interaction of G6b with SHP-1 and SHP-2.
authors.affiliation: Medical Research Council United Kingdom Human Genome Mapping Project Resource Center, Hinxton, Cambridge CB10 1SB, United Kingdom.
authors.forename: E C
authors.initials: EC
authors.lastname: de Vet
authors.forename: B
authors.initials: B
authors.lastname: Aguado
authors.forename: R D
authors.initials: RD
authors.lastname: Campbell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D005803:Genes, Immunoglobulin; D006031:Glycosylation; D047908:Intracellular Signaling Peptides and Proteins; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014638:Vanadates / Q000494:pharmacology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C119883:MPIG6B protein, human; D011971:Receptors, Immunologic; C076715:pervanadate; D014638:Vanadates; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases