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

We have identified KRP3, a novel kinesin-related protein expressed in the mammalian testis, and have examined the tissue distribution and subcellular localization of isoforms of this protein. Isolation of KRP3 clones, using the head domain identified in a previous PCR screen as probe, identified at least two KRP3 isoforms in the rat. We have isolated coding sequences of two highly related cDNAs from the rat testis that we have termed KRP3A and KRP3B (kinesin-related protein 3, A and B). Both cDNAs code for predicted polypeptides with the three-domain structure typical of kinesin superfamily members; namely a conserved motor domain, a region capable of forming a limited coiled-coil secondary structure, and a globular tail domain. Although almost identical in their head and stalk domains, these motors diverge in their tail domains. This group of motors is found in many tissues and cell types. The KRP3B motor contains DNA-binding motifs and an RCC1 (regulator of chromosome condensation 1) consensus sequence in its tail domain. Despite this similarity, KRP3B is not associated with the same structures as RCC1. Instead, KRP3 isoforms localize with the nuclei of developing spermatids, and their immunolocalization in the testis overlaps with that of the small GTPase Ran. Like Ran, KRP3 motors are associated in a polarized fashion with the nucleus of maturing spermatids at various stages of elongation. Our findings suggest a possible role for KRP3 motor isoforms in spermatid maturation mediated by possible interaction with the Ran GTPase.
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PMID:KRP3A and KRP3B: candidate motors in spermatid maturation in the seminiferous epithelium. 1187 94

We detail here how "free" centrosomes, lacking associated chromosomes, behave during mitosis in PtK(2) homokaryons stably expressing GFP-alpha-tubulin. As free centrosomes separate during prometaphase, their associated astral microtubules (Mts) interact to form a spindle-shaped array that is enriched for cytoplasmic dynein and Eg5. Over the next 30 min, these arrays become progressively depleted of Mts until the two centrosomes are linked by a single bundle, containing 10-20 Mts, that persists for > 60 min. The overlapping astral Mts within this bundle are loosely organized, and their plus ends terminate near its midzone, which is enriched for an ill-defined matrix material. At this time, the distance between the centrosomes is not defined by external forces because these organelles remain stationary when the bundle connecting them is severed by laser microsurgery. However, since the centrosomes move towards one another in response to monastrol treatment, the kinesin-like motor protein Eg5 is involved. From these results, we conclude that separating asters interact during prometaphase of mitosis to form a spindle-shaped Mt array, but that in the absence of chromosomes this array is unstable. An analysis of the existing data suggests that the stabilization of spindle Mts during mitosis in vertebrates does not involve the chromatin (i.e., the RCC1/RanGTP pathway), but instead some other chromosomal component, e.g., kinetochores.
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PMID:Separating centrosomes interact in the absence of associated chromosomes during mitosis in cultured vertebrate cells. 1211 53