Heterogeneity, distribution and endogenous phosphate content of KCl-myosins prepared from different parts of human brain.

Myosin concentrations and their endogenous phosphate (P) content as well as some of their properties were investigated in different parts of the central nervous system (CNS). Myosin concentration in hemispherial part is in the average 40 mg/100 g fresh mince, but it varies between 5 mg and 30 mg myosin depending on the mental activity or accidental brain diseases. This refers to the other parts of CNS, too. A myosin may be isolated with a single and sharp peak as far as the gel filtration profile is concerned in spite of the high lipid content of the brain. Working with minimal lipid and RNA content requires a careful procedure by an experienced person. In spite of any careful isolation procedure, purified KCl-myosin preparations are composed of at least two isomyosins each formed from different heavy chains. Myosins are localized in different parts of the cell, mitochondrial, synaptosomal and neuroplasmic, respectively. Brain myosins have higher endogeneous P concentrations than other cell-myosins. In hemispherial myosins the P-concentrations are high. Subjects trained in mental activities have the highest myosin and P concentration. We suggest that the role of myosin may directly be connected with cytokinetic motions even in case of the higher functions of brain cells like thinking, paying attention and memory, respectively.