Sherwin Y. Chan

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To study the role of protein kinase C (PKC) and its substrates in neuronal function, we have investigated the in vitro endogenous phosphorylation of the neuronal phosphoprotein F1 after induction of synaptic plasticity by long-term potentiation (LTP). The protein F1 phosphorylation was found to increase 5 min (Routtenberg et al., 1985), 1 hr (Lovinger et(More)
Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, used to methylate homocysteine in methionine biosynthesis. Methionine can be activated by ATP to give rise to the universal methyl donor, S-adenosylmethionine (AdoMet). Previously, a chimeric MTHFR (Chimera-1) comprised of the(More)
One-carbon flux into methionine and S-adenosylmethionine (AdoMet) is thought to be controlled at the methylenetetrahydrofolate reductase (MTHFR) step. Mammalian MTHFRs are inhibited by AdoMet in vitro, and it has been proposed that methyl group biogenesis is regulated in vivo by this feedback loop. In this work, we used metabolic engineering in the yeast(More)
Protein F1 is a neuron-specific, synaptic-enriched, membrane-bound substrate of protein kinase C (PKC) whose phosphorylation is related to synaptic plasticity in the adult. The sequence of 26 N-terminal amino acids was determined from purified rat protein F1. A 78-mer synthetic oligonucleotide designed from the partial N-terminal sequence enabled(More)
Adult polycystic kidney disease (APKD) is a common genetic disease with a frequency of 1:1000. Evidence suggests that transforming growth factor alpha (TGF alpha) signaling may contribute to the hyperproliferation of the cystic epithelia in APKD. TGF alpha and epidermal growth factor (EGF) are well known mitogens expressed in the kidney and both exert their(More)
Protein kinase C has been shown to be a phospholipid/Ca2+-dependent enzyme activated by diacylglycerol (Nishizuka, Y. (1984) Nature 308, 693-697; Nishizuka, Y. (1984) Science 225, 1365-1370). We have reported that unsaturated fatty acids (oleic acid and arachidonic acid) can activate protein kinase C independently of Ca2+ and phospholipid (Murakami, K., and(More)
Leaf extracts of 14-d-old pea (Pisum sativum L. cv Homesteader) seedlings were examined for folate derivatives and for 10-formyltetrahydrofolate synthetase (SYN), 5,10-methenyltetrahydrofolate cyclohydrolase (CYC), and 5,10-methylenetetrahydrofolate dehydrogenase (DHY) activities. Microbiological and enzyme assays showed that leaf folates SYN, CYC, and DHY(More)
RASSF1A is a tumor suppressor gene on 3p21.3 frequently inactivated by promoter hypermethylation in nasopharyngeal carcinoma (NPC). To identify RASSF1A target genes in NPC, we have investigated the expression profile of the stable RASSF1A transfectants and controls by high-density oligonucleotide array. A total of 57 genes showed differential expression in(More)