title: Further characterization of a conserved actin-binding 27-kDa fragment of actinogelin and alpha-actinins and mapping of their binding sites on the actin molecule by chemical cross-linking.
abstract: A conserved actin-binding domain (Mr = 27,000) of rat hepatic actinogelin, rat skeletal muscle, and chicken gizzard alpha-actinins (Mimura, N., and Asano, A. (1986) J. Biol. Chem. 261, 10680-10687) was separated into two components having different isoelectric points (peptides A and B) by chromatofocusing. Thermolysin digestion of peptide A generated peptide B with concomitant loss of peptide A. Amino acid compositions and tryptic maps of peptides A and B also demonstrated that peptide A is a precursor of peptide B upon thermolysin digestion. All of peptides A and B retained the activity to bind with F-actin competitively to each other. By the gel-filtration method, it was also shown that the native actin-binding 27-kDa fragments are monomeric and globular. The non-actin-binding 50- or 53.5-kDa fragment of actinogelin/alpha-actinins was, however, found to be asymmetric and dimeric in the native state. Chemical cross-linking of the 27-kDa fragment with F-actin with a water-soluble carbodiimide produced at least four different complexes (I-IV). Chemical cleaving analysis of the cross-linked products (complexes I and II) indicated that the 27-kDa fragment possesses two possible binding sites on actin at the NH2-terminal residues 1-12 (for complex I) and at residues spanning 86-119 or 123 (for complex II).
mesh_terms: D000185:Actinin / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D003432:Cross-Linking Reagents; D008840:Microfilament Proteins / Q000378:metabolism*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats
chemical_list: D000199:Actins; D003432:Cross-Linking Reagents; D008840:Microfilament Proteins; D010446:Peptide Fragments; C029354:actinogelin; D000185:Actinin