NOVEL ISOFORM OF BETA-1 INTEGRIN EXPRESSED IN SKELETAL AND CARDIAC-MUSCLE

We describe a novel isoform of the beta 1 integrin subunit called beta 1D, which contains a unique cytoplasmic domain, and is expressed spec ifically in skeletal and cardiac muscle. The beta 1D isoform arises fr om splicing into the final transcript of an additional exon located be tween exons 6 and 7. The nucleotide sequence of beta 1D predicts a cyt oplasmic domain of 50 amino acids in which the last 21 amino acids of the beta 1A integrin isoform are replaced by a related sequence of 24 amino acids. A beta 1D-specific anti-peptide polyclonal antibody was p repared and immunoprecipitation of tissue extracts with subsequent imm unoblotting showed expression of beta 1D isoform only in striated musc le cells. (C) 1995 Academic Press, Inc.