title: Isolation and characterization of baby hamster kidney (BHK-21) cell modulator protein.
abstract: A Ca2+-dependent modulator protein has been isolated from BHK-21 cells. The purification requires heat treatment, ion-exchange chromatography, and gel filtration. The protein appears homogenous on sodium dodecyl sulfate--polyacrylamide and isoelectric focusing gels. The protein comigrates with purified smooth muscle and brain modulators. BHK-21 modulator is characterized by a high content of aspartic and glutamic acids and by a high phenylalanine/tyrosine ratio. It lacks both cysteine and tryptophan. The protein is effective in activating brain-modulator-deficient phosphodiesterase. It can also be used in assay systems to generate Ca2+-sensitive actin activation of both BHK-21 and smooth muscle myosins. Therefore, it is proposed that the BHK-21 modulator protein is a component of the Ca2+-dependent  mechanism involved in the regulation of actin--myosin interactions in BHK-21 cells.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002147:Calmodulin / Q000302:isolation & purification / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D004789:Enzyme Activation; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D009218:Myosins / Q000378:metabolism; D013045:Species Specificity
chemical_list: D000199:Actins; D000596:Amino Acids; D002147:Calmodulin; D002352:Carrier Proteins; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D009218:Myosins