PMID: 22940583

Authors:

Dempsey BR, Rezvanpour A, Lee TW, Barber KR, Junop MS, Shaw GS

Title:

Structure of an asymmetric ternary protein complex provides insight for membrane interaction.

Journal:

Structure. 2012 Oct 10;20(10):1737-45. doi: 10.1016/j.str.2012.08.004. Epub 2012 , Aug 30.

Abstract:

Plasma membrane repair involves the coordinated effort of proteins and the inner phospholipid surface to mend the rupture and return the cell back to homeostasis. Here, we present the three-dimensional structure of a multiprotein complex that includes S100A10, annexin A2, and AHNAK, which along with dysferlin, functions in muscle and cardiac tissue repair. The 3.5 A resolution X-ray structure shows that a single region from the AHNAK C terminus is recruited by an S100A10-annexin A2 heterotetramer, forming an asymmetric ternary complex. The AHNAK peptide adopts a coil conformation that arches across the heterotetramer contacting both annexin A2 and S100A10 protomers with tight affinity ( approximately 30 nM) and establishing a structural rationale whereby both S100A10 and annexin proteins are needed in AHNAK recruitment. The structure evokes a model whereby AHNAK is targeted to the membrane surface through sandwiching of the binding region between the S100A10/annexin A2 complex and the phospholipid membrane.