Uptake and binding of /sup 125/I-calmodulin by isolated rat renal brush border membrane vesicles
The authors have investigated the interaction of /sup 125/I-calmodulin with isolated rat renal brush border membrane vesicles (BBV) using an experimental protocol which allows us to distinguish between ligand binding to the outside of the vesicles vs. uptake and possible binding to the vesicle interior. By examining the association of /sup 125/I-calmodulin with BBV as a function of medium osmolarity (300-1100 mosm) to alter intravesicular space, virtually all ligand interaction with BBV was found to represent uptake of intact /sup 125/I-calmodulin into the intravesicular space. Uptake appeared specific by the following criteria: (1) it was largely calcium dependent (2) it was inhibited in a dose dependent fashion by calmodulin and the homologous protein troponin C, but not by unrelated proteins (lysozyme, cytochrome C, insulin) (3) it was inhibited by known calmodulin antagonists (calmidazolium, mellitin, trifluoperazine). Calmodulin uptake may be followed by binding of /sup 125/I-calmodulin to intravesicular BBV proteins; calmodulin-binding proteins in BBV with molecular weights of 143K, 118K, 50K, 47.5K, 46.5K and 35K were identified by Western blotting techniques. The specific association of /sup 125/I-calmodulin with isolated BBV is of interest in regard to the possible role of this calcium regulatory protein in the protein reabsorptive and ion transport functions of this renal tubular membrane fraction.
- Research Organization:
- Univ. of Alabama, Birmingham
- OSTI ID:
- 6985862
- Report Number(s):
- CONF-8606151-; TRN: 86-039112
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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BIOCHEMICAL REACTION KINETICS
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CALCIUM COMPOUNDS
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DOSE-RESPONSE RELATIONSHIPS
INHIBITION
IODINE 125
KIDNEYS
LIGANDS
MOLECULAR WEIGHT
RATS
TRACER TECHNIQUES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
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DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
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MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
RADIOISOTOPES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques