title: Purification and characterization of cytoplasmic creatine kinase isozymes of Xenopus laevis.
abstract: The soluble creatine kinase isozymes CK-II, CK-III, and CK-IV from Xenopus laevis have been purified to apparent homogeneity and their subunits characterized by means of molecular weight, peptide pattern, and dissociation-reassociation experiments. CK-III and CK-IV are homodimeric isozymes whose subunits are distinct in both molecular weight (42,000 and 41,000, respectively) and Staphylococcus aureus V8 peptide pattern. In dissociation-reassociation experiments, those two subunits do form active heterodimeric isozymes with one another or with rabbit M-CK subunits. Hybrid CK-III/IV isozymes occur also during embryonic differentiation and in adult heart muscle, whereas most other adult tissues contain only homodimeric CK-III or CK-IV isozymes. The CK-II isozyme is a heterodimer composed of one CK-III subunit and another subunit specific to CK-II (Mr = 41,000). Neither in vivo nor in vitro does this subunit seem able to form homodimers or heterodimers with CK-IV and rabbit M-CK subunits. If we take into account the apparent association of CK-I isozyme with cellular organelles, these results corroborate earlier statements and suggest that the CK isozyme system of X. laevis is encoded by at least four differentially regulated genomic loci.
authors.affiliation: Laboratoire de Génétique Animale et Végétale, Université de Genève, Chêne-Bougeries, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Robert
authors.forename: H R
authors.initials: HR
authors.lastname: Kobel
mesh_terms: D000818:Animals; D003402:Creatine Kinase / Q000302:isolation & purification* / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004588:Electrophoresis, Cellulose Acetate; D005260:Female; D007527:Isoenzymes; D046911:Macromolecular Substances; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology; D010053:Ovary / Q000201:enzymology; D010449:Peptide Mapping; D055503:Protein Multimerization; D014982:Xenopus laevis
chemical_list: D007527:Isoenzymes; D046911:Macromolecular Substances; D003402:Creatine Kinase