CLONING OF THE BETA-3 CHAIN GENE (LAMB3) OF HUMAN LAMININ-5, A CANDIDATE GENE IN JUNCTIONAL EPIDERMOLYSIS-BULLOSA

Laminin 5 consists of three polypeptides, alpha 3, beta 3, and gamma 2 , encoded by the genes LAMA3, LAMB3, and LAMC2, respectively. In this study, we have elucidated the exon-intron organization of the human LA MBS gene. Characterization of five overlapping lambda phage DNA clones revealed that the gene was approximately 29 kb in size. Subsequent se quence data revealed that the gene consisted of 23 exons that varied f rom 64 to 379 bp in size, accounting for the full-length cDNA with an open reading frame of 3516 bp encoding 1172 amino acids. Comparison of the LAMBS gene structure with the previously characterized LAMB1 gene revealed that LAMB3 was considerably more compact. Knowledge of the e xon-intron organization of the LAMB3 gene will facilitate elucidation of mutations in patients with the junctional forms of epidermolysis bu llosa, some of which have been associated with mutations in the lamini n 5 genes. (C) 1995 Academic Press, Inc.