COLD-SENSITIVE MUTATIONS OF DICTYOSTELIUM MYOSIN HEAVY-CHAIN HIGHLIGHT FUNCTIONAL DOMAINS OF THE MYOSIN MOTOR

Dictyostelium provides a powerful environment for characterization of myosin II function. It provides well-established biochemical methods f or in vitro analysis of myosin's properties as well as an array of mol ecular genetic tools. The absence of myosin function results in an arr ay of phenotypes that can be used to genetically manipulate myosin fun ction. We have previously reported methods for the isolation and ident ification of rapid-effect cold-sensitive myosin II mutations in Dictyo stelium. Here, we report the development and utilization of a rapid me thod for localizing these point mutations. We have also sequenced 19 m utants. The mutations show distinct clustering with respect to three-d imensional location and biochemically characterized functional domains of the protein. We conclude that these mutants represent powerful too ls for understanding the mechanisms driving this protein motor.