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Giant axonal neuropathy (GAN) is an early-onset neurological disorder caused by mutations in the GAN

The vimentin N-terminal domain contains the sequence responsible for the interaction with mitochondria. The interaction of vimentin intermediate filaments with mitochondria causes the inhibition of their movements and contributes to their anchoring in cytoplasm.

Dictyostelium myosin is composed of two heavy chains and two pairs of light chains in a 1:1:1 stoichiometry. Myosin purified from amoebae grown in medium containing [32P hosphate had two of the subunits labeled (0.2-0.3 mol of phosphate per mol of 210,000-dalton heavy chain and #0.1 mol of phosphate r mol of 18,000-dalton light chain). Kinase activities specific or the 210,000-dalton and for the 18,000-dalton subunits have been identified in extracts of Dictyostelium amoebae, and the heavy chain kinase has been purified 50-fold. This kinase phosphorylated Dictyostelium myosin to a maximum of 0.5-1.0 mol of phosphate per mol of heavy chain. Heavy chain phosphate, but not light chain phosphate, can be removed with bacterial alkaline phosphatase. Actin-activated myosin ATPase increased 80% when phosphorylated myosin was dephosphorylated to a level of t0.06 mol of phosphate per mol of heavy chain. This effect could be reversed by rephosphorylating the myosin. The ability of myosin to self-assemble into thick filaments was inhibited by heavy chain phosphorylation. For example, in 80-100 mM KCI, only 10-20% of the myosin was assembled into thick filaments when the heavy chains were fully phosphorylated. Removal of the heavy chain phosphate resulted in 70-90% thick filament formation. This effect on self-assembly could be reversed by rephosphorylating the dephosphorylated myosin. These findings suggest that heavy chain phosphorylation may regulate cell contractile events by altering the state of myosin assembly. The contractile proteins actin and myosin, first studied in muscle, have been identified in various nonmuscle cells. Investigations using fluorescent probes have suggested that these proteins are involved in many cell functions including cell division, amoeboid movement, maintenance of cell shape, and translocation of cell surface proteins (for review, see refs.

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