title: Cross-linking of actin to myosin subfragment 1 in the presence of nucleotides.
abstract: Chemical cross-linking of actin to the 20K and 50K fragments of tryptically cleaved myosin subfragment 1 (S-1) by the zero-length cross-linking reagent 1-ethyl-3-[3-dimethylamino)propyl]carbodiimide (EDC) was used as a probe of the acto-S-1 interface in the presence of nucleotides. The course of the two reactions was monitored by measuring on sodium dodecyl sulfate (SDS)-polyacrylamide gels the time-dependent formation of the 20K-actin and 50K-actin cross-linked products. Both reactions were inhibited somewhat in the presence of MgADP, were slowed 3-4-fold in the presence of magnesium 5'-adenylyl imidodiphosphate (MgAMPPNP), and proceeded at least 7-fold slower with N,N'-p-phenylenedimaleimide (pPDM) modified S-1, as compared to the respective rates in the absence of nucleotides. However, neither the binding of the nucleotides MgADP and MgAMPPNP to S-1 nor the modification of S-1 by pPDM significantly changed the ratio of the cross-linking rates of actin to the 20K and 50K fragments. Similar to what was previously observed in the absence of nucleotides [Chen, T., Applegate, D., & Reisler, E. (1985) Biochemistry 24, 137-144], actin was cross-linked at an approximately 3-fold faster rate to the 20K fragment than to the 50K fragment under all reaction conditions tested. Thus, irrespective of the extent of acto-S-1 dissociation or the binding of nucleotides to acto-S-1, the 20K fragment remains the preferred cross-linking site for actin. These results show that the interaction of actin with each of the cross-linking sites on S-1 is not under selective or preferential control by nucleotides.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000227:Adenine Nucleotides / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000378:metabolism; D000818:Animals; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000494:pharmacology; D007700:Kinetics; D008301:Maleimides / Q000494:pharmacology; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism; D015879:Myosin Subfragments; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011817:Rabbits
chemical_list: D000199:Actins; D000227:Adenine Nucleotides; D003432:Cross-Linking Reagents; D008301:Maleimides; D015879:Myosin Subfragments; D010446:Peptide Fragments; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D009218:Myosins; D005022:Ethyldimethylaminopropyl Carbodiimide; C023860:N,N'-2-phenylenedimaleimide