Laminin is a basement membrane protein composed of 3 nonidentical chains, A (400 kD), B1 (230 kD), and B2 (220 kD), which are arranged in a cross-shaped structure. Mattei et al. (1989) used in situ hybridization to localize the human laminin A locus to chromosome 18p11.31.By study of mouse-Chinese hamster somatic cell hybrids, Kaye et al. assigned the gene for laminin A to mouse chromosome 17 and confirmed the assignment of the gene for laminin B2 to mouse chromosome 1. Haaparanta et al. reported the nucleotide sequence of LAMA cDNA. They found an open reading frame encoding 3,075 amino acids. Nissinen et al. reported that the complete human laminin A chain contains a 17-amino acid signal peptide and a 3,058-residue A chain proper. The chain has a distinct domain structure with numerous internal cysteine-rich repeats.