Cloning and Complete Primary Structure of the Mouse Laminin α3 Chain

doi:10.1074/jbc.270.37.21820

Cloning and Complete Primary Structure of the Mouse Laminin α3 Chain

DISTINCT EXPRESSION PATTERN OF THE LAMININ α3A AND α3B CHAIN ISOFORMS (*)

From the (1) U385 INSERM, Faculté de Médecine, 06107 Nice Cedex 2
(2) Institüt für Neuropathologie, Universität Zürich, 8093 Zürich, Switzerland, and
(3) Service de Dermatologie, Hôpital Pasteur, 06002 Nice Cedex 1, France

**To whom correspondence should be addressed. Tel.: 33-93-37-76-48; Fax: 33-93-81-14-04.

Abstract

We have isolated and characterized overlapping cDNA clones encoding the α3A and α3B chains of mouse laminin 5. Sequence analysis of the cDNA for the α3B 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 α chains identified thus far. The short arm of the α3B 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 α3A 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 α3B isoform and displays 77% conservative homology to the α3Ep 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 α3A and α3B isoforms, and in situ hybridization on mouse embryos revealed a focal localization of α3B in areas of the central nervous system.

Footnotes

↵^§ Contributed equally to this work.
↵^¶ Recipient of an E.E.C. Commission.
↵* This work was supported by grants from INSERM-CNAMTS, Fondation pour la Recherche Médicale (France), DEBRA Foundation (UK), Groupement de Recherche et d'Etude sur le Génome (GIP-GREG), Association Fran¸aise contre les Myopathies, and Association pour la Recherche sur le Cancer. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) X84013 [GenBank]and X84014[GenBank].
↵¹ The abbreviations used are:

kb

kilobase(s)

PCR

polymerase chain reaction

5′-RACE

5′-rapid amplification of cDNA ends

EGF

epidermal growth factor

ORF

open reading frame.
- Received May 8, 1995.
- Revision received July 12, 1995.