A1 Journal article – refereed

Effects of conformational activation of integrin alpha 1I and alpha 2I domains on selective recognition of laminin and collagen subtypes. – Integrin alpha I domain activation

Subtitle: Integrin alpha I domain activation

List of Authors: Tulla M, Lahti M, Puranen JS, Brandt A, Kapyla J, Domogatskaya A, Salminen TA, Tryggvason K, Johnson MS, Heino J

Publisher: Elsevier

Publication year: 2008

Journal: Experimental Cell Research

Journal acronym: Exp Cell Res

Volume number: 314

Issue number: 8

Number of pages: 10

ISSN: 0014-4827

DOI: http://dx.doi.org/http://dx.doi.org/10.1016/j.yexcr.2008.01.025

URL: http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=18377895&retmode=ref&cmd=prlinks

Collagen receptor integrins alpha 1 beta 1 and alpha 2 beta 1 can selectively recognize different collagen subtypes. Here we show that their alpha I domains can discriminate between laminin isoforms as well: alpha 1I and alpha 2I recognized laminin-111, -211 and -511, whereas their binding to laminin-411 was negligible. Residue Arg-218 in alpha1 was found to be instrumental in high-avidity binding. The gain-of-function mutation E318W makes the alpha 2I domain to adopt the "open" high-affinity conformation, while the wild-type alpha 2I domain favors the "closed" low-affinity conformation. The E318W mutation markedly increased alpha 2I domain binding to the laminins (-111, -211 and -511), leading us to propose that the activation state of the alpha 2 beta 1 integrin defines its role as a laminin receptor. However, neither wild-type nor alpha 2IE318W domain could bind to laminin-411. alpha 2IE318W also bound tighter to all collagens than alpha 2I wild-type, but it showed reduced ability to discriminate between collagens I, IV and IX. The corresponding mutation, E317A, in the alpha 1I domain transformed the domain into a high-avidity binder of collagens I and IV. Thus, our results indicate that conformational activation of integrin alpha 1I and alpha 2I domains leads to high-avidity binding to otherwise disfavored collagen subtypes.

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