Reversibly locking a protein fold in an active conformation with a disulfide bond: integrin alphaL I domains with high affinity and antagonist activity in vivo.

ABSTRACT: The integrin alphaLbeta2 has three different domains in its headpiece that have been suggested to either bind ligand or to regulate ligand binding. One of these, the inserted or I domain, has a fold similar to that of small G proteins. The I domain of the alphaM and alpha2 subunits has been crystallized in both open and closed conformations; however, the alphaL I domain has been crystallized in only the closed conformation. We hypothesized that the alphaL domain also would have an open conformation, and that this would be the ligand binding conformation. Therefore, we introduced pairs of cysteine residues to form disulfides that would lock the alphaL I domain in either the open or closed conformation. Locking the I domain open resulted in a 9,000-fold increase in affinity to intercellular

SUBMITTER: Shimaoka M 

PROVIDER: S-EPMC33413 | biostudies-literature | 2001 May

REPOSITORIES: biostudies-literature