| First Author | Barton KA | Year | 2009 |
| Journal | Biochemistry | Volume | 48 |
| Issue | 18 | Pages | 3956-66 |
| PubMed ID | 19296714 | Mgi Jnum | J:149371 |
| Mgi Id | MGI:3848382 | Doi | 10.1021/bi802203a |
| Citation | Barton KA, et al. (2009) Interactions between small heat shock protein alpha-crystallin and galectin-related interfiber protein (GRIFIN) in the ocular lens. Biochemistry 48(18):3956-66 |
| abstractText | As a member of the small heat shock protein superfamily, alpha-crystallin has a chaperone-like ability to recognize and bind denatured or unfolded proteins and prevent their aggregation. Recent studies suggest that alpha-crystallin may also interact with a variety of proteins under native conditions in vitro. To identify potential binding partners for alpha-crystallin in the intact ocular lens, we conducted cross-linking studies in transgenic mouse lenses designed for overexpression of His-tagged human alphaA-crystallin. Interacting proteins were copurified with the epitope-tagged crystallin complexes and were identified by tandem mass spectrometry. This approach identified GRIFIN (galectin-related interfiber protein) as a novel binding partner. Consistent with results from cross-linking, GRIFIN subunits copurified with alpha-crystallin complexes during size exclusion chromatography of nontransgenic mouse lens extracts prepared without chemical cross-linking. Equilibrium binding to GRIFIN was studied using native alpha-crystallin isolated from calf lenses as well as oligomeric complexes reconstituted from recombinant alphaA- and alphaB-crystallin subunits. Calf lens alpha-crystallin binds GRIFIN with relatively high affinity (K(d) = 6.5 +/- 0.8 microM) at a stoichiometry of 0.25 +/- 0.01 GRIFIN monomer/alpha-crystallin subunit. The binding interaction between alpha-crystallin and GRIFIN is enhanced up to 5-fold in the presence of 3 mM ATP. These binding data support the hypothesis that GRIFIN is a novel binding partner of alpha-crystallin in the lens. |
