ORCID Profile
0000-0003-3214-946X
Current Organisation
George Mason University
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Publisher: Elsevier BV
Date: 09-1993
DOI: 10.1016/0169-328X(93)90125-9
Abstract: We used oligonucleotide in situ hybridization and film autoradiography to quantitate the distributions of protein kinase C (PKC) alpha, beta, gamma, and epsilon mRNAs in subregions of rabbit hippoc us. Levels of each of the hippoc al PKC isozyme mRNAs and patterns of their regional distributions were remarkably invariant between in iduals. Within stratum pyramidale, the highest levels of PKC alpha mRNA were in the CA2 region, while PKC beta mRNA was maximally expressed in CA1, and PKC epsilon mRNA in CA3 PKC gamma mRNA was abundantly expressed throughout Ammon's horn. Previous experiments employing quantitative autoradiography for [3H]PDBU (Olds et al., Science, 245 (1989) 866-869) revealed an increase in membrane-bound PKC in the CA1 region of rabbit hippoc us up to 3 days following classical conditioning of the nictitating membrane response. We report here that there were no differences in levels of PKC alpha, beta, gamma, or epsilon mRNA between conditioned and control rabbits in any hippoc al region one day after training. These data are consistent with the hypothesis that PKC is post-translationally activated and translocated to the membrane during memory storage.
Publisher: Elsevier BV
Date: 11-1994
Abstract: Incorporation of exogenously applied fluorescent lipids into living cells was exploited to probe cellular structure and function in living hippoc al and cerebellar slices as assessed by fluorescent imaging techniques and intracellular recording. Nitrobenzoxadiole-phosphatidylcholine (NBD-PC) and BODIPY phorbol ester, in vitro substrates of phospholipase activity and protein kinase C, respectively, were incorporated and distributed into specific cell populations. In the hippoc al slice, both probes labeled the somata and proximal dendrites of pyramidal and granule cells but were hetrogeneously distributed across the different hippoc al fields. Changes in fluorescent properties of NBD-PC in in idual pyramidal cell and granule cell somata were quantified upon challenge with a muscarinic agonist known to modulate phospholipase A2 activity. In the cerebellar slice, both probes labeled Purkinje cell bodies and dendrites but only NBD-PC labeled stellate and granule cells. The cellular and functional specificity of these fluorescent lipid probes shows great promise for monitoring biochemical events in complex neuronal systems with significant spatial and temporal resolution.
Publisher: Proceedings of the National Academy of Sciences
Date: 26-11-1996
Abstract: A previously uncharacterized 22-kDa Ca 2+ -binding protein that also binds guanosine nucleotides was characterized, cloned, and analyzed by electrophysiological techniques. The cloned protein, calexcitin, contains two EF-hands and also has homology with GTP-binding proteins in the ADP ribosylation factor family. In addition to binding two molecules of Ca 2+ , calexcitin bound GTP and possessed GTPase activity. Calexcitin is also a high affinity substrate for protein kinase C. Application of calexcitin to the inner surface of inside-out patches of human fibroblast membranes, in the presence of Ca 2+ and the absence of endogenous Ca 2+ /calmodulin kinase type II or protein kinase C activity, reduced the mean open time and mean open probability of 115 ± 6 pS K + channels. Calexcitin thus appears to directly regulate K + channels. When microinjected into molluscan neurons or rabbit cerebellar Purkinje cell dendrites, calexcitin was highly effective in enhancing membrane excitability. Because calexcitin translocates to the cell membrane after phosphorylation, calexcitin could serve as a Ca 2+ -activated signaling molecule that increases cellular excitability, which would in turn increase Ca 2+ influx through the membrane. This is also the first known instance of a GTP-binding protein that binds Ca 2+ .
Location: United States of America
No related grants have been discovered for Jim Olds.