title: Lysine reactivities of tropomyosin complexed with troponin.
abstract: The relative reactivities of lysine residues of tropomyosin complexed with troponin have been measured in order to locate the binding site of troponin on tropomyosin in a complex between the two native proteins. The lysines were labeled with acetic anhydride using a competitive labeling procedure and the relative reactivities of tropomyosin lysine containing peptides were compared to those from tropomyosin labeled in the absence of troponin (S. E. Hitchcock-DeGregori, S. F. Lewis, and T. M.-T. Chou, (1985) Biochemistry 24, 3305-3314). Analysis of about two-thirds of the lysines indicates that troponin affects the reactivities of lysines along the length of the tropomyosin, indicating long-range effects. The inferred binding site is more extensive than previously reported, about 25 nm, extending from res. 136 to the carboxy-terminus and to res. 30 beyond the end-to-end overlap in the amino-terminal region of the next tropomyosin molecule.
mesh_terms: D000089:Acetic Anhydrides; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology; D008239:Lysine / Q000378:metabolism*; D009132:Muscles / Q000032:analysis*; D011487:Protein Conformation; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
chemical_list: D000089:Acetic Anhydrides; D014335:Tropomyosin; D014336:Troponin; C031800:acetic anhydride; D008239:Lysine; D002118:Calcium