Sequence and tissue distribution of the integrin alpha 9 subunit, a novel partner of beta 1 that is widely distributed in epithelia and muscle.
The integrin family of adhesion receptors consists of several heterodimeric glycoproteins, each composed of one alpha and one beta subunit. A novel integrin alpha subunit partial cDNA isolated from TGF-beta stimulated guinea pig airway epithelial cells has previously been reported (Erle, D.J., D. Sheppard, J. Bruess, C. Rüegg, and R. Pytela. 1991. Am. J. Respir. Cell Mol. Biol. 5:170-177). We have now determined cDNA and amino acid sequence for the human homolog of this subunit, named alpha 9, from a human lung cDNA library, a human small intestine cDNA library, and cDNA from the cell lines U937, HL-60 and Tera-2. This sequence is predicted to encode a 1006-amino acid mature protein that shares 39% identity with the previously identified integrin subunit alpha 4. By Northern blot analysis, alpha 9 mRNA was detected in the human carcinoma cell lines Tera-2 and Caco-2. Anti-peptide antibodies against the predicted COOH-terminal sequence of alpha 9 immunoprecipitated a heterodimer (140 kD/115 kD nonreduced; 150 kD/130 kD reduced) from Tera-2 lysates. Immunodepletion of beta 1-containing integrins with Tera-2 lysates removed alpha 9 immunoreactivity, suggesting that beta 1 is the principal beta subunit partner for alpha 9 in these cells. alpha 9 was detected by immunohistochemistry in airway epithelium, in the basal layer of squamous epithelium, and in smooth muscle, skeletal muscle, and hepatocytes.
Palmer
E L
EL
Lung Biology Center, University of California, San Francisco 94143.
Rüegg
C
C
Ferrando
R
R
Pytela
R
R
Sheppard
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D039001:Integrin alpha Chains; D016023:Integrins / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D039001:Integrin alpha Chains; D016023:Integrins; C084613:integrin alpha9; D004247:DNA