Actomyosin-like protein from brain separation and characterization of the actin-like component

1. Actin-like protein (neurin) has been separated from actomyosin-like protein (neurostenin) isolated from bovine brain. This was accomplished by gel filtration chromatography (Sephadex G-200) and by ultracentrifugation in a continuous sucrose gradient containing 0.6 M KI.

2. The actin-like protein stimulated the Mg²⁺-ATPase activity of muscle myosin.

3. It contained bound nucleotide which exchanged with free ¹⁴C]ATP.

4. It polymerized in the presence of 0.1 M KCl and 0.1 mM Mg²⁺ with release of P_i; increase in viscosity occurred upon dilution of the 0.6 M KI to 0.1 M.

5. The neurin reacted immunologically to form a single band with antiserum to neurostenin.

6. The neurin, similar to muscle actin, contained 3-methylhistidine.

7. The sedimentation constant of the protein was 2.8 S.