M. Koch et al., Characterization and expression of the laminin gamma 3 chain: A novel, non-basement membrane-associated, laminin chain, J CELL BIOL, 145(3), 1999, pp. 605-617
Laminins are heterotrimeric molecules composed of an alpha, a beta, and a g
amma chain; they have broad functional roles in development and in stabiliz
ing epithelial structures. Here, we identified a novel laminin, composed of
known alpha and beta chains but containing a novel gamma chain, gamma 3. W
e have cloned gene encoding this chain, LAMC3, which maps to chromosome 9 a
t q31-34. Protein and cDNA analyses demonstrate that gamma 3 contains all t
he expected domains of a gamma chain, including two consensus glycosylation
sites and a putative nidogen-binding site. This suggests that gamma 3-cont
aining laminins are likely to exist in a stable matrix.
Studies of the tissue distribution of gamma 3 chain show that it is broadly
expressed in: skin, heart, lung, and the reproductive tracts. In skin, gam
ma 3 protein is seen within the basement membrane of the dermal-epidermal j
unction at points of nerve penetration. The gamma 3 chain is also a promine
nt element of the apical surface of ciliated epithelial cells of: lung, ovi
duct, epididymis, ductus deferens, and seminiferous tubules. The distributi
on of gamma 3-containing laminins on the apical surfaces of a variety of ep
ithelial tissues is novel and suggests that they are not found within ultra
structurally defined basement membranes. It seems likely that these apical
laminins are important in the morphogenesis and structural stability of the
ciliated processes of these cells.