A NOVEL BETA-1 INTEGRIN ISOFORM PRODUCED BY ALTERNATIVE SPLICING - UNIQUE EXPRESSION IN CARDIAC AND SKELETAL-MUSCLE

The mRNA's of several integrin subunits are alternatively spliced in t he region encoding cytoplasmic domains, that may potentially provide a lternative integrin-cytoskeleton interactions and transmembrane signal ing pathways. We identified a novel cytoplasmic tail variant of the hu man beta 1 subunit by reverse transcriptase polymerase chain reaction. This fourth beta 1 variant, named beta 1D, is specific for skeletal a nd cardiac muscle. The determined genomic organization of the 3'-regio n of the human beta 1 gene reveals that beta 1D is produced by alterna tive splicing of mRNA. In addition, we show that the expression of bet a 1D is developmentally regulated during murine myoblast differentiati on, suggesting a role for beta 1D in myogenesis.