[Effect of the C-terminal actin-binding sites of caldesmon on the interaction of actin with myosin].
TRITC-phalloidin or FITC-labeled F-actin of ghost muscle fibers was bound to tropomyosin and C-terminal recombinant fragments of caldesmon CaDH1 (residues 506-793) or CaDH2 (residues 683-767). After that the fibers were decorated with myosin subfragment 1. In the absence of caldesmon fragments, subfragment 1 interaction with F-actin caused changes in parameters of polarized fluorescence, that were typical of "strong" binding of myosin heads to F-actin and of the "switched on" conformational state of actin. CaDH1 inhibited, whereas CaDH2 activated the effect of subfragment 1. It is suggested that C-terminal part of caldesmon may modulate the transition of F-actin subunits from the "switched on" to the "switched off" state.
Vikhorev
P G
PG
Institute of Cytology RAS, St. Petersburg.
Avrova
S V
SV
Ermakov
V S
VS
Copeland
O
O
Marston
S B
SB
Borovikov
Iu S
IuS
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D009218:Myosins / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011817:Rabbits
D000199:Actins; D002148:Calmodulin-Binding Proteins; D005456:Fluorescent Dyes; D009218:Myosins
Vliianie C-kontsevykh aktinsviazyvaiushchikh saĭtov kal'desmona na vzaimodeĭstvie aktina s miozinom.