Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 kinesin-like calmodulin binding protein (KCBP) is a new member of the kinesin superfamily that appears to be present only in plants. The KCBP is unique in its ability to interact with calmodulin in a Ca2+-dependent manner. To study the interaction of the KCBP with microtubules, we expressed different regions of the Arabidopsis KCBP and used the purified proteins in cosedimentation assays with microtubules. The motor domain with or without the calmodulin binding domain bound to microtubules. The binding of the motor domain containing the calmodulin binding region to microtubules was inhibited by Ca2+-calmodulin. This Ca2+-calmodulin regulation of motor domain interactions with microtubules was abolished in the presence of antibodies specific to the calmodulin binding region. In addition, the binding of the motor domain lacking the calmodulin binding region to microtubules was not inhibited in the presence of Ca2+-calmodulin, suggesting an essential role for the calmodulin binding region in Ca2+-calmodulin modulation. Results of the cosedimentation assays with the N-terminal tail suggest the presence of a second microtubule binding site on the KCBP. However, the interaction of the N-terminal tail region of the KCBP with microtubules was insensitive to ATP. These data on the interaction of the KCBP with microtubules provide new insights into the functioning of the KCBP in plants.
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PMID:Characterization of microtubule binding domains in the Arabidopsis kinesin-like calmodulin binding protein. 963 84

The kinesin family motor protein KCBP (kinesin-like calmodulin binding protein) was identified during a screen for Arabidopsis calmodulin-binding proteins [Reddy, et al., 1996b: J. Biol Chem. 271:7052-7060]. KCBP contains a C-terminal motor domain and is unique among kinesin motors in that it has a calmodulin-binding site. We expressed the KCBP motor domain in Escherichia coli and examined its microtubule (MT) binding and ATPase activity. KCBP bound MTs in an ATP-dependent manner and exhibited MT-stimulated ATPase activity. Ca2+/ calmodulin inhibited binding of KCBP to MTs under conditions that normally favor tight motor-MT interactions, and the extent of inhibition was dependent on the concentration of calcium and calmodulin. Ca2+/calmodulin did not affect KCBP's basal ATPase activity, but reduced the motor's MT-stimulated ATPase activity. The substantial reduction in affinity of KCBP for MTs in the presence of Ca2+/calmodulin suggests that Ca2+/calmodulin may modulate the activity of KCBP in vivo by regulating the motor's association with MTs. KCBP is the first MT-dependent motor protein found to be regulated by direct binding of Ca2+/calmodulin to its motor subunit.
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PMID:Ca2+/calmodulin regulation of the Arabidopsis kinesin-like calmodulin-binding protein. 971 69

The band 4.1 domain was first identified in the red blood cell protein band 4.1, and subsequently in ezrin, radixin, and moesin (ERM proteins) and other proteins, including tumor suppressor merlin/schwannomin, talin, unconventional myosins VIIa and X, and protein tyrosine phosphatases. Recently, the presence of a structurally related domain has been demonstrated in the N-terminal region of two groups of tyrosine kinases: the focal adhesion kinases (FAK) and the Janus kinases (JAK). Additional proteins containing the 4.1/JEF (JAK, ERM, FAK) domain include plant kinesin-like calmodulin-binding proteins (KCBP) and a number of uncharacterized open reading frames identified by systematic DNA sequencing. Phylogenetic analysis of amino acid sequences suggests that band 4.1/JEF domains can be grouped in several families that have probably diverged early during evolution. Hydrophobic cluster analysis indicates that the band 4.1/JEF domains might consist of a duplicated module of approximately 140 residues and a central hinge region. A conserved property of the domain is its capacity to bind to the membrane-proximal region of the C-terminal cytoplasmic tail of proteins with a single transmembrane segment. Many proteins with band 4.1/JEF domains undergo regulated intra- or intermolecular homotypic interactions. Additional properties common to band 4.1/JEF domains of several proteins are binding of phosphoinositides and regulation by GTPases of the Rho family. Many proteins with band 4. 1/JEF domains are associated with the actin-based cytoskeleton and are enriched at points of contact with other cells or the extracellular matrix, from which they can exert control over cell growth. Thus, proteins with band 4.1/JEF domain are at the crossroads between cytoskeletal organization and signal transduction in multicellular organisms. Their importance is underlined by the variety of diseases that can result from their mutations.
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PMID:Janus kinases and focal adhesion kinases play in the 4.1 band: a superfamily of band 4.1 domains important for cell structure and signal transduction. 999 Aug 61

Calponin is a basic smooth muscle protein capable of binding to actin, calmodulin, tropomyosin, and phospholipids. We have found that the basic calponin interacted with brain tubulin under polymerized and unpolymerized conditions in vitro [Fujii, T., Hiromori, T., Hamamoto, M., and Suzuki, T. (1997) J. Biochem. 122, 344-351]. We examined the calponin-binding site on the tubulin molecule by sedimentation, limited digestion, chemical-cross linking, immunoblotting, and delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometric (DE MALDI-TOF) analyses. Calponin interacts with both the alpha and beta tubulins and only slightly with the tyrosinated and acetylated form of alpha tubulin. The binding of calponin to microtubules was blocked by adding poly(L-aspartic acid) (PLAA) or MAP2. After digestion of microtubule proteins with subtilisin, the amount of calponin binding to alphabetas microtubules was reduced compared to native microtubules, but no further reduction was observed in the case of alphasbetas microtubules. The chemical cross-linked products of calponin and synthesized peptides (KDYEEVGVDSVEGE; alpha-KE) derived from the C-terminal region of alpha tubulin and (YQQYQDATADEQG; beta-YG) and (GEFEEEGEEDEA; beta-GA) from that of beta tubulin were detected by mass spectrometry. One kind of calponin-peptide complex was formed in the presence of alpha-KE or beta-YG, while five complexes (calponin:peptide = 1:1-5) were generated in the presence of beta-GA. Peptides alpha-KE and beta-GA inhibited the binding of calponin to tubulin produced by EDC in a concentration-dependent manner. These findings suggest that basic calponin interacts with both tubulin subunits and that their C-terminal regions, which also contain the binding sites of MAP2, tau, and kinesin, may be involved in calponin-binding.
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PMID:Identification of the binding region of basic calponin on alpha and beta tubulins. 1022 May 77

HIKE is a highly conserved sequence motif that selectively occurs in proteins candidate to bind PH domains, e.g., the beta subunit of heterotrimeric G proteins, kinases, ankyrin and kinesin. Thus, the HIKE region has been predicted to be a protein docking site for PH domains. This work evidentiates recent experimental evidence that unambiguously defines the functional role of HIKE in Gbeta as a multiple effector docking site and as a major regulatory region of G protein's function. Indeed, the Gbeta HIKE interacts with the beta-adrenergic receptor kinase, Galpha, Ggamma, adenylyl cyclase 2, phospholipase C beta2, inward rectifier K channels, calcium channel alpha1B, calmodulin, phosducin, ste20. Quite interestingly, HIKE is located in the Gbeta region that faces the cell membrane. Thus, HIKE also interacts with the cell membrane and may dynamically regulate membrane vs effector binding of the Galphabetagamma trimer. These findings fulfill a major prediction of the HIKE model, i.e., that HIKE is a regulatory region for protein-protein interactions. A role of HIKE as a proteic binding site for PH domains is supported by the profound influence of HIKE mutations on the largely PH-mediated binding of beta-ARK to Gbeta.
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PMID:HIKE, a candidate protein binding site for PH domains, is a major regulatory region of Gbeta proteins. 1032 71

In Arabidopsis and other plants there are multiple calmodulin isoforms. However, the role of these isoforms in regulating the activity of target proteins is obscure. Here, we analyzed the interaction between a kinesin-like calmodulin-binding motor protein (Reddy, A. S. N., Safadi, F., Narasimhulu, S. B., Golovkin, M., and Hu, X. (1996) J. Biol. Chem. 271, 7052-7060) and three calmodulin isoforms (calmodulin-2, -4, and -6) from Arabidopsis using different approaches. Gel mobility and fluorescence shift assays revealed that the motor binds to all calmodulin isoforms in a calcium-dependent manner. Furthermore, all calmodulin isoforms were able to activate bovine calcium/calmodulin-dependent phosphodiesterase. However, the concentration of calmodulin-2 required for half-maximal activation of phosphodiesterase is 2- and 6-fold lower compared with calmodulin-4 and -6, respectively. The dissociation constants of the motor to calmodulin-2, -4, and -6 are 12.8, 27.0, and 27.8 nM, respectively, indicating that calmodulin-2 has 2-fold higher affinity for the motor than calmodulin-4 and -6. Similar results were obtained using another assay that involves the binding of (35)S-labeled calmodulin isoforms to the motor. The binding saturation curves of the motor with calmodulin isoforms have confirmed that calmodulin-2 has 2-fold higher affinity to the motor. However, the affinity of calmodulin-4 and -6 isoforms for the motor was about the same. Based on these studies, we conclude that all calmodulin isoforms bind to the motor protein but with different affinities.
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PMID:Interaction of a kinesin-like protein with calmodulin isoforms from Arabidopsis. 1053 84

Several novel members of the kinesin superfamily, until now identified only in plants, are unique in their ability to bind calmodulin in the presence of Ca(2+). Here, we identify the first such kinesin in an animal system. Sequence analysis of this new motor, called kinesin-C, predicts that it is a large carboxy-terminal kinesin, 1624 amino acid residues in length, with a predicted molecular mass of 181 kDa. Kinesin-C is predicted to contain a kinesin motor domain at its carboxy terminus, linked to a segment of alpha-helical coiled-coil 950 amino acid residues long, ending with an amino-terminal proline-rich tail domain. A putative calmodulin-binding domain resides at the extreme carboxy terminus of the motor polypeptide, and recombinant kinesin-C binds to a calmodulin-affinity column in a Ca(2+)-dependent fashion. The presence of this novel calmodulin-binding motor in sea urchin embryos suggests that it plays a critical role in Ca(2+)-dependent events during early sea urchin development.
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PMID:Identification of kinesin-C, a calmodulin-binding carboxy-terminal kinesin in animal (Strongylocentrotus purpuratus) cells. 1055 23

Kinesin-like calmodulin-binding protein (KCBP), a novel kinesin-like protein from plants, is unique among kinesins and kinesin-like proteins in having a calmodulin-binding domain adjacent to its motor domain. KCBP localizes to mitotic microtubule (MT) arrays including the preprophase band, the spindle apparatus, and the phragmoplast, suggesting a role for KCBP in establishing these MT arrays by bundling MTs. To determine if KCBP bundles MTs, we expressed C-terminal motor and N-terminal tail domains of KCBP, and used the purified proteins in MT bundling assays. The 1.5 C protein with the motor and calmodulin-binding domains induced MT bundling. The 1.5 C-induced bundles were dissociated in the presence of Ca(2+)/calmodulin. Similar results were obtained with a 1.4 C protein, which lacks much of the coiled-coil region present in 1.5 C protein and does not form dimers. The N-terminal tail of KCBP, which contains an ATP-independent MT binding site, is also capable of bundling MTs. These results, together with the KCBP localization data, suggest the involvement of KCBP in establishing mitotic MT arrays during different stages of cell division and that Ca(2+)/calmodulin regulates the formation of these MT arrays.
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PMID:Bundling of microtubules by motor and tail domains of a kinesin-like calmodulin-binding protein from Arabidopsis: regulation by Ca(2+)/Calmodulin. 1062 99

Kinesin-like calmodulin-binding protein (KCBP) is a novel member of the kinesin superfamily that is involved in cell division and trichome morphogenesis. KCBP is unique among all known kinesins in having a myosin tail homology-4 region in the N-terminal tail and a calmodulin-binding region following the motor domain. Calcium, through calmodulin, has been shown to negatively regulate the interaction of KCBP with microtubules. Here we have used the yeast two-hybrid system to identify the proteins that interact with the tail region of KCBP. A protein kinase (KCBP-interacting protein kinase (KIPK)) was found to interact specifically with the tail region of KCBP. KIPK is related to a group of protein kinases specific to plants that has an additional sequence between subdomains VII and VIII of the conserved C-terminal catalytic domain and an extensive N-terminal region. The catalytic domain alone of KIPK interacted weakly with the N-terminal KCBP protein but strongly with full-length KCBP, whereas the noncatalytic region did not interact with either protein. The interaction of KCBP with KIPK was confirmed using coprecipitation assays. Using bacterially expressed full-length and truncated proteins, we have shown that the catalytic domain is capable of phosphorylating itself. The association of KIPK with KCBP suggests regulation of KCBP or KCBP-associated proteins by phosphorylation and/or that KCBP is involved in targeting KIPK to its proper cellular location.
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PMID:Interaction of a kinesin-like calmodulin-binding protein with a protein kinase. 1078 94

The kinesin-like calmodulin (CaM) binding protein (KCBP), a minus end-directed microtubule motor protein unique to plants, has been implicated in cell division. KCBP is negatively regulated by Ca(2)+ and CaM, and antibodies raised against the CaM binding region inhibit CaM binding to KCBP in vitro; therefore, these antibodies can be used to activate KCBP constitutively. Injection of these antibodies into Tradescantia virginiana stamen hair cells during late prophase induces breakdown of the nuclear envelope within 2 to 10 min and leads the cell into prometaphase. However, mitosis is arrested, and the cell does not progress into anaphase. Injection of antibodies later during cell division has no effect on anaphase transition but causes aberrant phragmoplast formation and delays the completion of cytokinesis by approximately 15 min. These effects are achieved without any apparent degradation of the microtubule cytoskeleton. We propose that during nuclear envelope breakdown and anaphase, activated KCBP promotes the formation of a converging bipolar spindle by sliding and bundling microtubules. During metaphase and telophase, we suggest that its activity is downregulated.
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PMID:The kinesin-like calmodulin binding protein is differentially involved in cell division. 1097 Jan 40


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