FAST AXOPLASMIC TRANSPORT OF A CALCIUM-BINDING PROTEIN IN MAMMALIAN NERVE |
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Authors: | Zafar Iqbal Sidney Ochs |
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Affiliation: | Department of Physiology, and the Medical Biophysics Program, Indiana University School of Medicine, Indianapolis, IN, U.S.A. |
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Abstract: | Abstract— Calcium is transported at a fast rate of 410 mm/day in cat sciatic nerve on injection of 45Ca2+ into the L7 dorsal root ganglia. Nerve segments corresponding to the crest and the plateau regions of transported activity were analyzed by column chromatography on Sephadex G-100 and Biogel A 5m columns and the fast transported 45Ca2+ found to be bound to a protein of 15,000 dalton. Using [3H]leucine as a precursor, a labeled calcium binding protein (CaBP) was found located at the same position in elution volumes from the columns as was the protein-bound 45Ca2 +. The level of [3H]-labeled CaBP in the crest and plateau regions were compared using column chromatography and polyacrylamide gel electrophoresis techniques and approx 3×4 times more [3H]-labeled activity was found in the crest as compared to the plateau. These findings indicate that Ca2+ is fast transported in association with the CaBP. The relation of CaBP to the transport filament model of axoplasmic transport and its possible role in nerve are discussed. |
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