Structural Aspects of Troponin-Tropomyosin Regulation of Skeletal Muscle Contraction

PERSPECTIVES AND OVERVIEW . . . . . . . . . . . . ..... ... . . . . ... . . . . . . . . . . . . . . . . . . . .. . . . ... . . ... . . . . . . . . . . . . . . . . . . . . . ... . . . . . 535 THE THIN FILAMENT . ..... , .... , .... , ... .. ,., ,., .. .. ,', ... .. , ....... •.. .. 536 TROPONIN 537 Troponin C . . . ... . ..... . . . . . . ... ... . . . . . . . . . . . . . . . . ... . .... . . ... . . ........ . . ... . . . . . . ..... 537 Troponin ! ........ ... . . . .... . 543 Troponin T , 544 TROPOMYOSIN . . . ..... 545 INTERACTIONS OF REGULATORY PROTEINS . . . . . . . . ... . . ... . . . . . . . ... . ... . . . . . . . . . ...... 547 Tropomyosin-Actin ...... .... 547 TnT-Tropomyosin . ... . . ... . ... . . .... . ... . . ... . .... . ... . . ... . . .... . . . . . . ... . ......... . ... . .... . ... . .... . .... 548 TnT-TnC and TnT-Tn! 550 TnCTn! and Tn!-Actin . . . . . . . . ... 552 REGULATORY MECHANiSMS 553