title: A 115 kDa calmodulin-binding protein is located in rat liver endosome fractions.
abstract: The distribution of calmodulin-binding polypeptides in various rat liver subcellular fractions was investigated. Plasma-membrane, endosome, Golgi and lysosome fractions were prepared by established procedures. The calmodulin-binding polypeptides present in the subcellular fractions were identified by using an overlay technique after transfer from gels to nitrocellulose sheets. Distinctive populations of calmodulin-binding polypeptides were present in all the fractions examined except lysosomes. A major 115 kDa calmodulin-binding polypeptide of pI 4.3 was located to the endosome subfractions, and it emerges as a candidate endosome-specific protein. Partitioning of endosome fractions between aqueous and Triton X-114 phases indicated that the calmodulin-binding polypeptide was hydrophobic. Major calmodulin-binding polypeptides of 140 and 240 kDa and minor polypeptides of 40-60 kDa were present in plasma membranes. The distribution of calmodulin in the various endosome and plasma-membrane fractions was also analysed, and the results indicated that the amounts were high compared with those in the cytosol.
authors.affiliation: Laboratory of Protein Structure, National Institute for Medical Research, London, U.K.
authors.forename: C
authors.initials: C
authors.lastname: Enrich
authors.forename: O
authors.initials: O
authors.lastname: Bachs
authors.forename: W H
authors.initials: WH
authors.lastname: Evans
mesh_terms: D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D007425:Intracellular Membranes / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D010455:Peptides / Q000032:analysis / Q000378:metabolism; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D002148:Calmodulin-Binding Proteins; D010455:Peptides