title: Molecular cloning of the mouse integrin beta 7 subunit.
abstract: The complete analysis of a cDNA clone encoding the mouse integrin beta 7 subunit that was isolated from a lambda gt10 cDNA library prepared from interleukin-4-activated mouse spleen B cells is reported. The 805-amino acid sequence deduced from the cDNA revealed a signal peptide, a 704-amino acid extracellular domain with eight N-glycosylation sites, a transmembrane domain, and a 61-amino acid intracellular domain. Several structural features were conserved with other integrin beta chains including the four cysteine-rich epidermal growth factor-like repeat sequences in the extracellular domain. Comparative analysis of the mouse and human beta 7 subunits revealed 87% sequence identity with conservation of three potential intracellular tyrosine phosphorylation sites. The cDNA hybridized to two mRNA transcripts of 3 and 2 kilobases (kb) in size. The 3-kb transcript, which is considered the productive form, was found in T and B leukemic cell lines, a macrophage line, and a mastocytoma cell line. Suprisingly, the smaller 2-kb transcript, which seems unlikely to encode a complete beta 7 protein, was found expressed in epithelial cells cultured from mouse skin. The integrin beta 7 subunit displays sequence identity with the beta subunit of the M290 antigen found expressed almost exclusively on intraepithelial lymphocytes in the small intestine suggesting that beta 7 may play an adhesive role in intraepithelial lymphocytes immunosurveillance of the gut mucosa. The cellular distribution of beta 7 transcripts is more extensive than the T-lineage-restricted distribution of the M290 antigen, indicating that beta 7 may be the common beta subunit for more than one receptor or that translation of beta 7 transcripts varies in different cell types.
authors.affiliation: Department of Molecular Medicine, School of Medicine, University of Auckland, New Zealand.
authors.forename: Q
authors.initials: Q
authors.lastname: Yuan
authors.forename: W M
authors.initials: WM
authors.lastname: Jiang
authors.forename: E
authors.initials: E
authors.lastname: Leung
authors.forename: D
authors.initials: D
authors.lastname: Hollander
authors.forename: J D
authors.initials: JD
authors.lastname: Watson
authors.forename: G W
authors.initials: GW
authors.lastname: Krissansen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D016023:Integrins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010766:Phosphorylation; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D016023:Integrins; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D004247:DNA