Cloning and sequence of the cDNA encoding the β4 integrin subunit in rat peripheral nerve

β4 and α6 integrin subunits dimerize to form an adhesion receptor that is necessary to nucleate hemidesmosomes and to anchor epithelial cells to their basal laminae. β4 is also expressed in Schwann cells (which do not contain hemidesmosomes) in peripheral nerve, where it may function in the formation or maintenance of myelin. The cDNA for β4 integrin has been cloned from epithelia-derived human and mouse tissues. We cloned cDNAs encoding β4 integrin from libraries derived from rat peripheral nerve, and determined the complete nucleotide sequence encoding the signal peptide and mature protein. Comparison of the deduced amino acid (aa) sequence revealed 95.1% and 87.5% identity with the mouse and human epithelia-derived sequences, respectively. The amino acid sequence of postulated signal transduction domains in β4 was 100% identical among rat, mouse, and human. Our cDNA clones included two of the four postulated alternatively spliced variants previously described in epithelial clones. Despite the potentially diverse functions of β4 integrin in Schwann cells and keratinocytes, the cDNAs for nerve-derived β4 integrin are highly similar to those cloned from epithelia.