Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell membrane contact induces the de novo expression of choline O-acetyltransferase (CAT; acetyl-CoA: choline O-acetyltransferase, EC 2.3.1.6) activity in cultures of virtually pure neonatal rat dissociated sympathetic neurons. To identify molecular mechanisms underlying membrane-associated CAT induction, the responsible membrane component was characterized and partially purified. Substantial CAT-inducing activity was found in membranes from adult rat spinal cord and sensory and sympathetic ganglia. Whole brain membranes demonstrated significantly less activity. CAT induction in sympathetic neurons in response to spinal cord membranes was linear with respect to time, after an initial 6-hr lag. It was also linear with respect to concentrations of spinal cord protein from 2 to 100 micrograms per ml. CAT-inducing activity was extracted from spinal cord membranes by incubation with 100 mM NaCl and was purified approximately 5000-fold by DEAE ion-exchange and gel filtration chromatography. The active factor appears to be an extrinsic protein with an apparent molecular mass of 27 kDa. It is inactivated by trypsin and chymotrypsin but is moderately thermostable, retaining activity at 60 degrees C but not at 90 degrees C.
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PMID:Partial purification and characterization of a membrane-derived factor regulating neurotransmitter phenotypic expression. 256 90

Choline acetyltransferase (Acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6, abbreviated ChAT), the biosynthetic enzyme for acetylcholine and acetylcholinesterase (EC 3.1.1.7, abbreviated AChE) are expressed in a human cholinergic neuroblastoma cell line, MC-IXC. We have shown that ChAT activity can be regulated in culture by retinoic acid, an active metabolite of vitamin A, and by sodium butyrate, an organic fatty acid. Optimal concentrations of these agents produce 4.3-fold and 1.6-fold increases in ChAT activity, respectively. The effects of retinoic acid are statistically significant after 24 h, whereas for sodium butyrate significant differences are seen only after 48 h. Since retinoic acid stimulation of ChAT activity was reversed only by trypsin treatment and not by removal of retinoic acid from the medium, this suggests that this agent may be acting at the level of the cell surface. Other differentiating conditions, such as culture in serum-free medium or addition of 1-2% dimethylsulfoxide did not increase ChAT activity. Acetylcholinesterase activity was shown to increase only in the presence of sodium butyrate, suggesting that retinoic acid and sodium butyrate may be acting via different pathways. Retinoic acid and sodium butyrate both seem to be permissive rather than instructive in regulating ChAT activity in that they are unable to induce ChAT expression de novo in cell lines which do not already express ChAT activity.
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PMID:Stimulation of choline acetyltransferase activity by retinoic acid and sodium butyrate in a cultured human neuroblastoma. 292 23