Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A second NF1 messenger differing in the GAP domain was recently described. This type II transcript contains an internal additional sequence consisting of an open reading frame, in phase with the preceding and the following sequences and predicts a 21 amino acid addition in the catalytic domain of NF1 protein. In this report we present analysis of the two forms of NF1 transcripts in several normal human tissues and in primary neurofibromatosis tumors. Our results indicate (i) that the type II NF1 messenger displaying the additional exon is very widely expressed in all the normal adult tissues tested, (ii) that it is the form of NF1 messenger expressed in peripheral nerve and neurofibromas, and (iii) that the additional sequence could encode for a peptide related to a nucleoside triphosphatase.
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PMID:The neurofibromatosis 1 gene transcripts expressed in peripheral nerve and neurofibromas bear the additional exon located in the GAP domain. 128 Jan 27

The gene for von Recklinghausen neurofibromatosis (NF1) was recently identified by positional cloning and found to code for a large, ubiquitously expressed protein. This protein has both structural and functional similarity to a family of proteins with guanosine triphosphatase-activating properties, involved in the regulation of the protooncogene ras. One of the postulated functions of the NF1 gene product may relate to its ability to regulate ras-mediated cell proliferation. Selective pharmacotherapy directed at downregulating ras may be of benefit to patients with NF1.
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PMID:Recent progress toward understanding the molecular biology of von Recklinghausen neurofibromatosis. 159 91

Guanosine triphosphatase (GTPase) activity of Ras is increased by interaction with Ras-GAP (GTPase-activating protein) or with the GAP-related domain of the type 1 neurofibromatosis protein (NF1-GRD), but Ras is not affected by interaction with cytoplasmic and membrane forms of Rap-GAP; Rap1A, whose effector function can suppress transformation by Ras, is sensitive to both forms of Rap-GAP and resistant to Ras-GAP and NF1-GRD. A series of chimeric proteins composed of portions of Ras and Rap were constructed; some were sensitive to Ras-GAP but resistant to NF1-GRD, and others were sensitive to cytoplasmic Rap-GAP but resistant to membrane Rap-GAP. Sensitivity of chimeras to Ras-GAP and cytoplasmic Rap-GAP was mediated by amino acids that are carboxyl-terminal to the effector region. Residues 61 to 65 of Ras conferred Ras-GAP sensitivity, but a larger number of Rap1A residues were required for sensitivity to cytoplasmic Rap-GAP. Chimeras carrying the Ras effector region that were sensitive only to Ras-GAP or only to cytoplasmic Rap-GAP transformed NIH 3T3 cells poorly. Thus, distinct amino acids of Ras and Rap1A mediate sensitivity to each of the proteins with GAP activity, and transforming potential of Ras and sensitivity of Ras to Ras-GAP are at least partially independent properties.
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PMID:Heterogeneous amino acids in Ras and Rap1A specifying sensitivity to GAP proteins. 174 34

Ras-GAP (GTPase activating protein) is a regulatory protein that stimulates the intrinsic guanosine triphosphatase (GTPase) activity of the proto-oncogene product p21ras. A domain of the neurofibromatosis gene product (NF1) that has sequence similarity to the catalytic domain of Ras-GAP and to yeast IRA gene products also has a specific stimulatory activity toward p21ras GTPase. Arachidonic acid and phosphatidic acid inactivate GAP, but no agents have been identified that stimulate GAP and thereby switch p21ras off. With the use of recombinant Ha-c-Ras and Ras-GAP, NF1, and GAP catalytic domains, it was found that prostaglandins PGF2 alpha and PGA2 stimulated Ras-GAP and that prostacyclin PGI2 inhibited Ras-GAP. The stimulatory effect of PGF2 alpha was saturable and structure-specific and competed with the inhibitory effect of arachidonic acid. Arachidonic acid also inhibited the catalytic activity of NF1, but prostaglandins were not stimulatory. These results suggest a mechanism for the allosteric control of Ras function through the modulation of arachidonate metabolism.
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PMID:Regulation of Ras-GAP and the neurofibromatosis-1 gene product by eicosanoids. 190 23