Characterization of the ligand-binding specificities of integrin alpha3beta1 and alpha6beta1 using a panel of purified laminin isoforms containing distinct alpha chains.
Integrins alpha3beta1 and alpha6beta1 are two major laminin receptors expressed on the surface of mammalian cells. Interactions of cells with laminins through these integrins play important roles in cell adhesion, differentiation, motility, and matrix assembly. To determine the binding specificity and affinity of these integrins toward various types of laminins at the level of direct protein-protein interactions, we purified integrins alpha3beta1 and alpha6beta1 from human placenta, and examined their binding to a panel of laminin isoforms, each containing distinct alpha chains (i.e., laminin-1, laminin-2/4, laminin-5, laminin-8, and laminin-10/11). Integrin alpha3beta1 showed clear specificity for laminin-5 and laminin-10/11, with no significant binding to laminin-1, laminin-2/4, and laminin-8. In contrast, integrin alpha6beta1 showed a broad spectrum of specificity, with apparent binding affinity in the following order: laminin-10/11 > laminin-5 > laminin-1 > laminin-2/4 congruent with laminin-8. Integrin titration assays demonstrated that laminin-10/11 was the most preferred ligand among the five distinct laminin isoforms for both alpha3beta1 and alpha6beta1 integrins. Given that laminin-10/11 is the major basement membrane component of many adult tissues, the interaction of laminin-10/11 with these integrins should play a central role in the adhesive interactions of epithelial cells with underlying basement membranes.
Nishiuchi
Ryoko
R
Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871.
Murayama
Ohoshi
O
Fujiwara
Hironobu
H
Gu
Jianguo
J
Kawakami
Toru
T
Aimoto
Saburo
S
Wada
Yoshinao
Y
Sekiguchi
Kiyotoshi
K
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D039201:Integrin alpha3beta1 / Q000378:metabolism*; D039121:Integrin alpha6beta1 / Q000378:metabolism*; D016023:Integrins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D007797:Laminin / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008081:Liposomes / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D017077:Culture Media, Conditioned; D039201:Integrin alpha3beta1; D039121:Integrin alpha6beta1; D016023:Integrins; D007797:Laminin; D008024:Ligands; D008081:Liposomes; D010455:Peptides; D020033:Protein Isoforms; D000097794:Kalinin; C119013:laminin 10