Cargando…

Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody

The integrin VLA-2 was previously found to bind to either collagen alone, or collagen plus laminin, but the mechanism for this cell- specific functional difference was unknown. Here we transfected VLA-2 alpha 2 subunit cDNA into K562 cells and obtained VLA-2 (called Form-O) which bound to neither co...

Descripción completa

Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1993
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119525/
https://www.ncbi.nlm.nih.gov/pubmed/8421065
_version_ 1782141281323974656
collection PubMed
description The integrin VLA-2 was previously found to bind to either collagen alone, or collagen plus laminin, but the mechanism for this cell- specific functional difference was unknown. Here we transfected VLA-2 alpha 2 subunit cDNA into K562 cells and obtained VLA-2 (called Form-O) which bound to neither collagen nor laminin. We then used a Matrigel selection procedure to enrich for a minor subpopulation of K562 cells stably expressing a form of VLA-2 (Form-C) that bound to collagen but not laminin. In contrast, the same alpha 2 cDNA transfected into RD cells yielded VLA-2 (Form-CL) which bound to both collagen and laminin. These Form-O, -C, and -CL activities were stably expressed during extended cell culture, and could not be qualitatively altered by adding phorbol esters or by exchaning the resident divalent cations. However, addition of stimulatory anti-beta 1 antibodies (TS2/16, A-1A5) rapidly converted VLA-2 Form-O and Form-C into Form-CL. Anti-beta 1 antibody stimulation of VLA-2 activity was observed not only on whole cells, but also with solubilized receptors. These results suggest (a) that the ligand binding specificity of VLA-2 can be determined by its cellular environment, rather than by variations in the primary sequence of the alpha 2 subunit, (b) that stably inactive or partly active VLA-2 can be rapidly converted to a fully active form through conformational changes initiated at a nonligand binding site on the beta 1 subunit, and (c) that the mechanisms for VLA-2 stimulation by phorbol ester and by antibody are quite distinct, because the latter does not require an intact cell.
format Text
id pubmed-2119525
institution National Center for Biotechnology Information
language English
publishDate 1993
publisher The Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-21195252008-05-01 Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody J Cell Biol Articles The integrin VLA-2 was previously found to bind to either collagen alone, or collagen plus laminin, but the mechanism for this cell- specific functional difference was unknown. Here we transfected VLA-2 alpha 2 subunit cDNA into K562 cells and obtained VLA-2 (called Form-O) which bound to neither collagen nor laminin. We then used a Matrigel selection procedure to enrich for a minor subpopulation of K562 cells stably expressing a form of VLA-2 (Form-C) that bound to collagen but not laminin. In contrast, the same alpha 2 cDNA transfected into RD cells yielded VLA-2 (Form-CL) which bound to both collagen and laminin. These Form-O, -C, and -CL activities were stably expressed during extended cell culture, and could not be qualitatively altered by adding phorbol esters or by exchaning the resident divalent cations. However, addition of stimulatory anti-beta 1 antibodies (TS2/16, A-1A5) rapidly converted VLA-2 Form-O and Form-C into Form-CL. Anti-beta 1 antibody stimulation of VLA-2 activity was observed not only on whole cells, but also with solubilized receptors. These results suggest (a) that the ligand binding specificity of VLA-2 can be determined by its cellular environment, rather than by variations in the primary sequence of the alpha 2 subunit, (b) that stably inactive or partly active VLA-2 can be rapidly converted to a fully active form through conformational changes initiated at a nonligand binding site on the beta 1 subunit, and (c) that the mechanisms for VLA-2 stimulation by phorbol ester and by antibody are quite distinct, because the latter does not require an intact cell. The Rockefeller University Press 1993-01-02 /pmc/articles/PMC2119525/ /pubmed/8421065 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title_full Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title_fullStr Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title_full_unstemmed Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title_short Multiple functional forms of the integrin VLA-2 can be derived from a single alpha 2 cDNA clone: interconversion of forms induced by an anti- beta 1 antibody
title_sort multiple functional forms of the integrin vla-2 can be derived from a single alpha 2 cdna clone: interconversion of forms induced by an anti- beta 1 antibody
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119525/
https://www.ncbi.nlm.nih.gov/pubmed/8421065