Some properties of the actomyosin-like protein of the uterus

Comparatively little work has been done on the protein extractable from uterus muscle under con- ditions similar to those used for extracting acto- myosin from skeletalmuscle. Csapo (1949, 1950a, b) has used 0'5M-KCI extracts of rat, rabbit and human uterus and, by comparing the viscosity before and after addition of adenosine triphosphate (ATP) with the viscosity of skeletal-muscle extracts similarly treated, has concluded that uterus muscle contains actomyosin but less than that in skeletal muscle. Csapo (1949, 1950a, b) has correlated this actomyosin content with functional activity in different states of the uterus. Schwalm, Cretius & Lange (1955) have studied variations in the viscosity response to ATP of extracts made with M-KC1 from human uteri in different states.