Cell type-specific integrin variants with alternative alpha chain cytoplasmic domains.

Tamura RN, Cooper HM, Collo G, Quaranta V
Proc Natl Acad Sci U S A. 1991 88 (22): 10183-7

PMID: 1946438 · PMCID: PMC52892 · DOI:10.1073/pnas.88.22.10183

The integrin heterodimers composed of the alpha 6 subunit with the beta 1 or beta 4 subunit (alpha 6 beta 1 and alpha 6 beta 4) are receptors for laminin and basement membrane components, respectively. The alpha 3 beta 1 integrin recognizes laminin, collagen, fibronectin, or epiligrin. We report the identification of structural variants (A and B) of the alpha 6 and alpha 3 subunits, containing distinct cytoplasmic domains. The expression of one cytoplasmic domain or the other, based probably on alternative exon usage, is cell-type dependent. Most transformed cell lines express both alpha 6A and alpha 6B isoforms, as determined by mRNA amplification or antibody immunoprecipitation. In contrast, embryonic fibroblasts express exclusively alpha 6A, and embryonic stem cells express exclusively alpha 6B. In most normal tissues, both alpha 6 isoforms are detectable, but several tissues express either alpha 6A or alpha 6B. The alpha 3B mRNA was amplified from heart and brain, while all other tissues and cell lines tested contained only alpha 3A mRNA. Alternative cytoplasmic domains may provide a means for varying the cellular responses to the ligands of alpha 6 and alpha 3 integrins according to the cell type.

MeSH Terms (18)

Amino Acid Sequence Animals Base Sequence Cell Line Cloning, Molecular Cricetinae Cytoplasm Gene Expression Genetic Variation Humans Immunoblotting Integrins Macromolecular Substances Molecular Sequence Data Oligodeoxyribonucleotides Polymerase Chain Reaction RNA, Messenger Sequence Homology, Nucleic Acid

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