The repeat has the consensus sequence GDV(K/Q/R)(T/S/G)X(R/K/T) WLFETXPLD. This repeat motif is typically found in the N-terminus of the proteins, with a copy number between 2 and 28 repeats. Direct evidence for binding to and stabilising F-actin has been found [1] in the human protein Swiss:Q702N9. The homologues in mouse and chicken localise in the adherens junction complex of the intercalated disc in cardiac muscle and in the myotendon junction of skeletal muscle. mXin may co-localise with Vinculin which is known to attach the actin to the cytoplasmic membrane [1]. It has been shown that the amino-terminus of human xin (CMYA1) binds the EVH1 domain of Mena/VASP/EVL, and the carboxy-terminus binds the, for the filamin family unique, domain 20 of filaminC [4]. This confirms the proposed role of xin repeat containing proteins as F-actin-binding adapter proteins.

1: Localization of the novel Xin protein to the adherens junction complex in cardiac and skeletal muscle during development. Sinn HW, Balsamo J, Lilien J, Lin JJ; Dev Dyn 2002;225:1-13. PMID:12203715

2: Xin repeats define a novel actin-binding motif. Pacholsky D, Vakeel P, Himmel M, Lowe T, Stradal T, Rottner K, Furst DO, van der Ven PF; J Cell Sci 2004;117:5257-5268. PMID:15454575

3: Xin-repeats and nebulin-like repeats bind to F-actin in a similar manner. Cherepanova O, Orlova A, Galkin VE, van der Ven PF, Furst DO, Jin JP, Egelman EH; J Mol Biol. 2006;356:714-723. PMID:16384582

4: Unusual splicing events result in distinct Xin isoforms that associate differentially with filamin c and Mena/VASP. van der Ven PF, Ehler E, Vakeel P, Eulitz S, Schenk JA, Milting H, Micheel B, Furst DO; Exp Cell Res. 2006;312:2154-2167. PMID:16631741