Vitamin D-dependent rat renal calcium-binding protein: development of a radioimmunoassay, tissue distribution, and immunologic identification

Journal Article · Wed Aug 01 04:00:00 EDT 1984 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-115-2-640· OSTI ID:6350271

Sonnenberg, J; Pansini, A R; Christakos, S

A sensitive double antibody RIA has been developed for the 28,000 mol wt rat renal vitamin D-dependent calcium-binding protein. Using this assay, concentrations of calcium-binding protein (CaBP) as low as 30 ng can be measured. The assay is precise (intraassay variability, 5.0%) and reproductible (interassay variability, 8.2%). Measurements of renal CaBP by RIA showed a good correlation with measurements of CaBP by the chelex resin assay and by polyacrylamide gel analysis by densitometric tracing using a purified CaBP marker. The concentration of CaBP in the vitamin D-replete rat kidney is 7.3 +/- 1.0 (mean +/- SEM) micrograms/mg protein. In vitamin D-deficient rats the level of renal CaBP is 2.6 +/- 0.3 micrograms/mg protein. Tissue distribution of immunoreactive rat renal CaBP showed the highest concentration of CaBP in the rat cerebellum (38.3 +/- 5.1 micrograms/mg protein). Lower concentrations of immunoreactive CaBP were detected in several other rat tissues. No immunoreactive CaBP was detected in rat or human serum. In necropsy human kidney and cerebellum, high levels of immunoreactive CaBP were also detected (1.5 +/- 0.1 and 27.3 +/- 2.1 micrograms/mg protein, respectively). When extracts of rat kidney and brain and human cerebellum and kidney were assayed at several dilutions, immunodisplacement curves parallel to that of pure renal CaBP were observed, indicating immunochemical similarity. Fractionation of extracts of rat cerebellum, human kidney, and human cerebellum on Sephadex G-100 revealed immunoreactivity and calcium-binding activity in the 28,000 mol wt region similar to rat kidney.

• Research Organization: Univ. of Medicine and Dentistry of New Jersey, Newark
• OSTI ID: 6350271
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 115:2; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
ANIMALS
BLOOD SERUM
BODY
BRAIN
CALCIUM
CENTRAL NERVOUS SYSTEM
CEREBELLUM
CHEMICAL BONDS
DISTRIBUTION
ELEMENTS
IMMUNE SERUMS
IMMUNOLOGY
ISOTOPE APPLICATIONS
KIDNEYS
MAMMALS
MAN
MEASURING METHODS
METALS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PRIMATES
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RATS
RODENTS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
VERTEBRATES
VITAMIN D
VITAMINS