Cloning and Complete Primary Structure of the Mouse Laminin α3 Chain: DISTINCT EXPRESSION PATTERN OF THE LAMININ α3A AND α3B CHAIN ISOFORMS

Marie-Florence Galliano,Daniel Aberdam,Adriano Aguzzi,Jean-Paul Ortonne,Guerrino Meneguzzi

doi:10.1074/jbc.270.37.21820

Marie-Florence Galliano, Daniel Aberdam + Show 3 more

Open Access

https://doi.org/10.1074/jbc.270.37.21820

Copy DOI

Abstract

We have isolated and characterized overlapping cDNA clones encoding the alpha 3A and alpha 3B chains of mouse laminin 5. Sequence analysis of the cDNA for the alpha 3B predicts a polypeptide of 2541 amino acids (279,510 Da) comprising a truncated short arm and a carboxyl-terminal long arm common to the laminin alpha chains identified thus far. The short arm of the alpha 3B chain harbors two alternating epidermal growth factor-like domains and two globular domains. The amino-terminal globular domain, thought to mediate interactions with molecules of the extracellular matrix, shows no significant homology to any globular domain at the tips of the known laminin isoforms. The alpha 3A cDNA predicts a polypeptide of 1711 amino acids (186,230 Da) that substitutes a short sequence of 43 amino acids for the short arm seen in the alpha 3B isoform and displays 77% conservative homology to the alpha 3Ep chains of the adhesion ligand epiligrin. Northern and Western blot analyses of skin and lung epithelial cells demonstrated the tissue-specific expression of the laminin alpha 3A and alpha 3B isoforms, and in situ hybridization on mouse embryos revealed a focal localization of alpha 3B in areas of the central nervous system.

Highlights

We have isolated and characterized overlapping cDNA clones encoding the ␣3A and ␣3B chains of mouse laminin 5
The ␣3A cDNA predicts a polypeptide of 1711 amino acids (186,230 Da) that substitutes a short sequence of 43 amino acids for the short arm seen in the ␣3B isoform and displays 77% conservative homology to the ␣3Ep chains of the adhesion ligand epiligrin
Sequence analysis revealed that these cDNA clones represent two distinct transcripts, designated as ␣3A and ␣3B, homologous to the epiligrin ␣3EpA and ␣3EpB chain isoforms, respectively (Ryan et al, 1994)

Summary

Introduction

We have isolated and characterized overlapping cDNA clones encoding the ␣3A and ␣3B chains of mouse laminin 5. Sequence analysis of the cDNA for the ␣3B predicts a polypeptide of 2541 amino acids (279,510 Da) comprising a truncated short arm and a carboxyl-terminal long arm common to the laminin ␣ chains identified far. Laminins are noncollagenous components of basement membranes that mediate cell adhesion, growth, migration, and differentiation These cross-shaped molecules constitute a family of proteins consisting of three individual polypeptide chains joined together in a long arm as coiled-coil amphipatic ␣-helices linked by interchain disulfide bonds. Laminin chain variants with specific patterns of temporal and spatial expression have been identified in different species All these isoforms are highly homologous, in that their short arms are comprised of globular domains and characteristic epidermal growth factor-like domains, and their long arms. Chains belonging to a different class combine into a trimeric molecule presenting with a large globular domain G contributed by the carboxyl terminus of the ␣ chain

Methods

Results

Conclusion