Molecular cloning and expression of the cDNA for alpha 3 subunit of human alpha 3 beta 1 (VLA-3), an integrin receptor for fibronectin, laminin, and collagen.
alpha 3 beta 1 (VLA-3), a member of the integrin family of cell adhesion receptors, may function as a receptor for fibronectin, laminin, and collagen. A partial cDNA clone (2.4 kb) for the human alpha 3 subunit was selected from an endothelial cell lambda gt11 cDNA library by specific antibody screening. Several overlapping cDNA clones were subsequently obtained, of a total length of 4.6 kb from various cDNA libraries. The reconstructed alpha 3 cDNA was expressed on the surface of chinese hamster ovary cells as detected by an alpha 3-specific mAb after transfection, suggesting that the cDNA is authentic. Within this sequence was an open reading frame, encoding for 1,051 amino acids, including a signal peptide of 32 residues, a long extracellular domain (959 residues), a transmembrane domain (28 residues), and a short cytoplasmic segment (32 residues). Overall, the alpha 3 amino acid sequence was 25-37% similar to the other integrin alpha subunits that are cleaved, with most similarity to the alpha 6 sequence (37%), and less similarity to those alpha subunits that have I domains (15-20%, excluding the I domain sequence itself). Features most like those in other alpha subunits are (a) the positions of 18/19 cysteine residues, (b) three potential metal binding domains of the general structure DX(D/N)X(D/N)GXXD, and (c) the predicted transmembrane domain. The mass of alpha 3 calculated from its amino acid sequence is 113,505. The human alpha 3 sequence was 89% identical to hamster galactoprotein b3, and 70% similar to the chicken CSAT antigen band 2 protein partial sequence, suggesting that these two polypeptides are homologues of human alpha 3.
Takada
Y
Y
Research Institute of Scripps Clinic, La Jolla, California 92037.
Murphy
E
E
Pil
P
P
Chen
C
C
Ginsberg
M H
MH
Hemler
M E
ME
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D038981:Receptors, Collagen; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000235:genetics; D017474:Receptors, Laminin; D016029:Receptors, Very Late Antigen / Q000235:genetics*; D011994:Recombinant Proteins; D015183:Restriction Mapping; D016415:Sequence Alignment
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D038981:Receptors, Collagen; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D017474:Receptors, Laminin; D016029:Receptors, Very Late Antigen; D011994:Recombinant Proteins; D004247:DNA