Table 1.

Actomyosin techniques discussed in this review—a quick comparison

Technique	Strengths	Weaknesses
In vitro motility assay	Gives quantitative measure of unloaded velocities	Does not quantify the effect of load on myosin function
	Simple experimental set up
	Small quantities of purified protein (<1 µg)
	Good first screen to identify effect of mutation
Steady state ATPase assay	Characterizes the effect of mutation on the ATP cycle time and apparent affinities for actin and for ATP	Larger quantities of protein needed (~1 mg)
		Stopped flow techniques are needed to measure kinetic substeps in the ATPase cycle
	Well established bulk assay
Optical tweezers	Directly quantify the effect of mechanical load on myosin function	Sophisticated instrumentation for dual-beam optical trap set up
	Quantitative measurement of effect of mutation on force generation of myosin
Single cell dynamic force–length measurements	Measure the effect of the mutation on an intact beating cardiomyocyte	Sophisticated instrumentation for force and length measurements
		Cell attachment and measurements are trickly, requiring technical expertise for reproducible measurements
	Characterize the effect of single mutations in myosin at the sarcomeric level