A significant fraction (>30%, saturable around 90%) of brain myosin II, but not skeletal or cardiac muscle myosin II, binds to lipid vesicles composed of the anionic phospholipid L-a-phosphatidyl-L-serine.
Brain myosin II, unlike cardiac or skeletal muscle myosin II, can bind directly to anionic phospholipids, suggesting a mechanism for its role in neuronal cell motility.
Myosin II has been observed in close proximity to the neuronal plasma membrane, suggesting the possibility that at least one isoform of neuronal myosin II may be capable of direct association. Here, we demonstrate that a significant fraction (> 30%, saturable around 90%) of brain myosin II, but not myosins from skeletal or cardiac muscle, can bind to lipid vesicles composed of the anionic phospholipid L-alpha-phosphatidyl-L-serine but not with vesicles made from the neutral phospholipid L-alpha-phosphatidylcholine. Binding to lipid vesicles made from L-alpha-phosphatidyl-L-serine is enhanced in the presence of millimolar amounts of free calcium. ATPase activity remains unimpaired after vesicle association. Myosin II was also shown to remain in tight association with purified plasma membranes, even after depletion of actin. The above observations suggest that mechanisms involving membrane-bound myosin II are required to facilitate metazoan cell motility.
Li et al. (1994) studied this question. Brain myosin II vs. Skeletal or cardiac muscle myosin II was evaluated on Binding to lipid vesicles composed of L-a-phosphatidyl-L-serine. A significant fraction (>30%, saturable around 90%) of brain myosin II, but not skeletal or cardiac muscle myosin II, binds to lipid vesicles composed of the anionic phospholipid L-a-phosphatidyl-L-serine.