Identification of high-affinity calmodulin-binding proteins in rat liver
The Ca/sup 2 +/-dependent binding of (/sup 125/I) calmodulin (CaM) to hepatic proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was utilized to identify CaM binding or acceptor proteins or CAPs. Two proteins of apparent molecular weight of 60,000 (CAP-60) and 45,000 (CAP-45) comprised > 80% of the Ca/sup 2 +/-dependent CaM binding in rat liver cytosol. CAP-60 and CAP-45 were partially purified by a variety of chromatographic steps, including affinity chromatography on CaM Sepharose. CAP-60 possessed a native molecular size of 400,000, indicating it to be the CaM-binding subunit of a larger oligomeric complex. In contrast, CAP-45 was monomeric as judged by gel filtration. Neither CAP-60 nor CAP-45 possessed chromatographic properties consistent with known CaM-dependent enzymes reported in the literature. Two-dimensional peptide mapping provided convincing evidence that CAP-60 and CAP-45 were unrelated to other well-characterized CAPs, namely Ca/sup 2 +/ (CaM)-dependent protein kinase II, calcineurin, or the CaM-dependent cyclic nucleotide phosphodiesterase. The relative abundance and high affinity for CaM could suggest that these novel target proteins, CAP-60 and CAP-45, represent a dominant pathway for CaM action in the mammalian liver.
- Research Organization:
- Univ. of Texas Medical School, Houston
- OSTI ID:
- 5445428
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
LIVER
BIOCHEMISTRY
PROTEINS
AUTORADIOGRAPHY
MOLECULAR WEIGHT
AMP
ATP
CALCIUM COMPOUNDS
CATIONS
ELECTROPHORESIS
IODINE 125
PHOSPHORUS 32
RATS
TRITIUM COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CHARGED PARTICLES
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
IONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS ISOTOPES
RADIOISOTOPES
RODENTS
VERTEBRATES
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