Cloning and expression of the mouse laminin gamma 2 (B2t) chain, a subunit of epithelial cell laminin.
We have isolated and sequenced the full-length cDNA for the mouse laminin gamma 2 chain and mapped it to mouse Chromosome 1 proximal to laminin gamma 1. The mRNA for the mouse gamma 2 spans 5.2 kb and codes for a 1192-residue amino acid polypeptide. The gamma 2 chain (formerly termed laminin B2t), a homologue of gamma 1 (formerly B2), lacks an N-terminal domain and has a shorter domain III in comparison to the laminin gamma 1 chain. The expression of the laminin gamma 2 and gamma 1 chains in both newborn and fetal mice was examined by both Northern analysis and in situ hybridization. mRNA for the laminin gamma 2 chain was expressed specifically by epithelial cells in many tissues with a particularly high level of expression in the tongue, hair follicles, lung and kidney. In contrast, a high level of expression of the laminin gamma 1 chain mRNA was seen in both epithelial and endothelial cells in these tissues. In addition, gamma 1 mRNA was expressed in other tissues such as the nasal septum, blood vessels, and the muscle of the tongue. Immunohistochemistry with an anti-gamma 2 IgG detected strong expression of the laminin gamma 2 chain in the basement membrane of the collecting tubules of the kidney and of the pancreas. Immunoprecipitation studies with antibodies to the gamma 2 chain detected three species at 165, 155 and 140 kDa in HT-1080 cell-conditioned media. This protein complex is characteristic of the kalinin (nicein/epiligrin) complex, and provides further evidence that these proteins are identical and that the gamma 2 chain is the subunit of the epithelial-cell-specific laminin.
Sugiyama
S
S
Laboratory of Developmental Biology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Utani
A
A
Yamada
S
S
Kozak
C A
CA
Yamada
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000302:isolation & purification; D004622:Embryo, Mammalian / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D017403:In Situ Hybridization; D007797:Laminin / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis
D018076:DNA, Complementary; D007074:Immunoglobulin G; D007797:Laminin; D012333:RNA, Messenger