title: Protein from macrophages inhibiting polymerization of actin.
abstract: The crude cytoplasmic extracts of macrophages showed a low actin-polymerization activity as compared with the purified actin preparations. This suggested that an actin-polymerization inhibitor should exist in the crude cytoplasmic extracts of macrophages. Thus, the isolation of actin-polymerization inhibiting protein from the crude extract was attempted. The protein with a high actin-polymerization inhibiting activity had a molecular weight of 65,000 daltons as determined by polyacrylamide gel electrophoresis in dodecyl sulfate, a Stokes radius of 33.8 A as measured by gel filtration and a sedimentation coefficient of 4.9 S as determined by analytical centrifugation. The actin-polymerization inhibiting activity was much higher in 0.1 M KCl than in 0.6 M KCl. It was not affected by either the presence or the absence of free Ca2+. It was considered that the protein is responsible for the large proportion of unpolymerized actin in the crude extract of macrophages.
mesh_terms: D000199:Actins / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003593:Cytoplasm / Q000032:analysis; D008264:Macrophages / Q000032:analysis*; D008970:Molecular Weight; D011108:Polymers; D011189:Potassium Chloride / Q000494:pharmacology; D011506:Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D011817:Rabbits
chemical_list: D000199:Actins; D011108:Polymers; D011506:Proteins; D011189:Potassium Chloride