Restoration of defective mechanochemical properties of cleaved actins by native tropomyosin: involvement of the 40-50 loop in subdomain 2 of actin in interaction with myosin and tropomyosin.
Native tropomyosin activated sliding movement in vitro of F-actin with ATP by 30%. Actin cleaved at the 40-50 loop by subtilisin or proteinase K slid on HMM much slower than intact actin, but native tropomyosin strikingly recovered this defective motility of cleaved actin by 2 to 3 times. On the other hand, with ATP analogues of CTP and ITP, sliding movements of cleaved actin and particularly intact actin were inhibited by native tropomyosin, indicating that native tropomyosin augmented specificity of the myosin substrate of NTP. These results suggested that the 40-50 loop in the small domain 2 of actin interacted directly or indirectly with tropomyosin and play a significant role in cross talk between myosin and native tropomyosin.
Higashi-Fujime
S
S
Department of Molecular Biology, Faculty of Science, Nagoya University, Japan. j46031a@nucc.cc.nagoya-u.ac.jp
Hozumi
T
T
D017766:Acid Anhydride Hydrolases / Q000378:metabolism; D000199:Actins / Q000737:chemistry* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003570:Cytidine Triphosphate / Q000494:pharmacology; D007293:Inosine Triphosphate / Q000494:pharmacology; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology; D009218:Myosins / Q000378:metabolism*; D043583:Nucleoside-Triphosphatase; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism*
D000199:Actins; D014335:Tropomyosin; D007293:Inosine Triphosphate; D003570:Cytidine Triphosphate; D000255:Adenosine Triphosphate; D017766:Acid Anhydride Hydrolases; D043583:Nucleoside-Triphosphatase; D009218:Myosins