Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanochemical ATPase kinesin is thought to move membrane-bounded organelles along microtubules in fast axonal transport. However, fast transport includes several classes of organelles moving at rates that differ by an order of magnitude. Further, the fact that cytoplasmic forms of kinesin exist suggests that kinesins might move cytoplasmic structures such as the cytoskeleton. To define cellular roles for kinesin, the axonal transport of kinesin was characterized. Retinal proteins were pulse-labeled, and movement of radiolabeled kinesin through optic nerve and tract into the terminals was monitored by immunoprecipitation. Heavy and light chains of kinesin appeared in nerve and tract at times consistent with fast transport. Little or no kinesin moved with slow axonal transport indicating that effectively all axonal kinesin is associated with membranous organelles. Both kinesin heavy chain molecular weight variants of 130,000 and 124,000 M(r) (KHC-A and KHC-B) moved in fast anterograde transport, but KHC-A moved at 5-6 times the rate of KHC-B. KHC-A cotransported with the synaptic vesicle marker synaptophysin, while a portion of KHC-B cotransported with the mitochondrial marker hexokinase. These results suggest that KHC-A is enriched on small tubulovesicular structures like synaptic vesicles and that at least one form of KHC-B is predominantly on mitochondria. Biochemical specialization may target kinesins to appropriate organelles and facilitate differential regulation of transport.
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PMID:Fast axonal transport of kinesin in the rat visual system: functionality of kinesin heavy chain isoforms. 753 59

We have synthesized 2'-deoxy-2'-iodoadenosine-5'-triphosphate (2'-IATP), a heavy-atom analog of adenosine-5'-triphosphate. This compound was made for X-ray structural studies to target the nucleotide site of ATP binding proteins. It was diffused successfully into crystals of the microtubule-based motor proteins ncd (non-claret disjunctional protein from Drosophila melanogaster) and kinesin. With ncd, the nucleotide binding site was 70% occupied and the crystals were able to diffract X-rays to 2.5 A. The iodo-analog provided a useful isomorphous derivative with overall phasing power 1.89 in the range of 25.0-2.5 A. With kinesin, 2'-IATP co-crystallized with the protein. The crystals diffracted to at least 2.8 A with a phasing power of 1.73 in the range of 20.0-5.0 A. The analog was also found to be a substrate for all of the enzymes tested, including creatine kinase, pyruvate kinase, hexokinase, and myosin, with values of Km and Vmax that were within a factor of 10 of those for ATP. The analog supported muscle contraction, relaxing fibers, and producing active tension with values not statistically different from those obtained with ATP. These results all suggest that this analog should be useful for providing a heavy-atom derivative for crystals of enzymes that bind ATP.
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PMID:A novel adenosine triphosphate analog with a heavy atom to target the nucleotide binding site of proteins. 852 80