Disease relevance of Khc

• Derivative K448-BIO contains the 448 N-terminal residues of Drosophila kinesin heavy chain fused at the C terminus to a 2-residue linker and a C-terminal fragment from Escherichia coli biotin carboxyl carrier protein; derivative K448-L is the same except that it lacks the biotin carboxyl carrier protein fragment [1].
• The kinesin-enriched fractions were subjected to preparative SDS-PAGE, and the band representing the kinesin heavy chain was excised, homogenized, and subjected to partial enzymatic digestion with Staphylococcus aureus V8 protease [2].

Psychiatry related information on Khc

• Kinesin motor activity is dependent on the presence of ATP and microtubules [3].

High impact information on Khc

• The in vivo function of the microtubule motor protein kinesin was examined in Drosophila using genetics and immunolocalization [4].
• The data indicate that kinesin function is essential and suggest that kinesin has an important role in the neuromuscular system, perhaps as a motor for axonal transport [4].
• Kinesin heavy chain is essential for viability and neuromuscular functions in Drosophila, but mutants show no defects in mitosis [4].
• The possibility of more general cellular functions remains open, but observation of embryogenesis and morphogenesis in khc mutants suggests that mitosis and the cell cycle can proceed in spite of impaired kinesin function [4].
• Analyses of this new sequence suggest that the maximal motor unit in the kinesin superfamily may be as little as 350 amino acids, and that the existence of both kinesin and kinesin-like molecules must be an evolutionarily ancient feature of eukaryotes [5].

Biological context of Khc

• Axonal transport of mitochondria requires milton to recruit kinesin heavy chain and is light chain independent [6].
• Kinesin light chain-independent function of the Kinesin heavy chain in cytoplasmic streaming and posterior localisation in the Drosophila oocyte [7].
• To identify proteins that mediate or regulate kinesin-cargo interactions, we have performed yeast two-hybrid screens of a Drosophila embryonic cDNA library, using the tetratricopeptide repeats of the kinesin light chain and amino acids 675-975 of the kinesin heavy chain as baits [8].
• Previous work has shown that mutation of the gene that encodes the microtubule motor subunit kinesin heavy chain (Khc) in Drosophila inhibits neuronal sodium channel activity, action potentials and neurotransmitter secretion [9].
• Antibodies were generated against peptides based on two regions of the amino acid sequence of Drosophila kinesin: the ATPase active site (amino acids 86-99) in the head of the kinesin heavy chain and the tail of the heavy chain (residues 913-933) [10].

Anatomical context of Khc

• The recruitment of KHC to mitochondria is, in part, determined by the NH(2) terminus-splicing variant of milton [6].
• Thus, the Kinesin heavy chain can function independently of the light chain in the oocyte, indicating that it associates with its cargoes by a novel mechanism [7].
• Dynein and the actin cytoskeleton control kinesin-driven cytoplasmic streaming in Drosophila oocytes [11].
• Khc mutations also impair the development of larval motor axon terminals, causing dystrophic morphology and marked reductions in synaptic bouton numbers [9].
• Affinity purification and subcellular localization of kinesin in human neutrophils [10].

Associations of Khc with chemical compounds

• Here, we show that lipid giant unilamellar vesicles (GUVs), to which kinesin molecules have been attached by means of small polystyrene beads, give rise to membrane tubes and to complex tubular networks when incubated in vitro with microtubules and ATP [12].
• A kinesin switch I arginine to lysine mutation rescues microtubule function [13].
• In previous work, we examined the nucleotide dependence of motility and enzymatic activity by kinesin [Shimizu, T., Furusawa, K., Ohashi, S., Toyoshima, Y. Y., Okuno, M., Malik, F., & Vale, R. D., (1991) J. Cell Biol. 112, 1189-1197] [14].
• We investigated the kinesin stepping mechanism by immobilizing a Drosophila kinesin derivative through the carboxyl-terminal end of the neck coiled-coil domain and measuring orientations of microtubules moved by single enzyme molecules at submicromolar adenosine triphosphate concentrations [15].
• Kinesin is a mechanochemical protein that converts the chemical energy in adenosine triphosphate into mechanical force for movement of cellular components along microtubules [16].

Physical interactions of Khc

• Pull-down assays reveal that Liprin-alpha interacts with Drosophila Kinesin-1 (Khc) but not dynein [17].
• A function for kinesin I in the posterior transport of oskar mRNA and Staufen protein [18].
• Thus, KLP68D may be used for anterograde axonal transport and could conceivably move cargoes in fly neurons different than those moved by kinesin heavy chain or other plus-end directed motors [19].
• Thus, a complex containing oskar mRNA and Staufen may be transported along microtubules to the posterior pole by kinesin I [18].

Regulatory relationships of Khc

• Khc mutations that reduce the velocity of kinesin-1 transport in vitro blocked streaming yet still supported posterior localization of oskar mRNA, suggesting that streaming is not essential for the oskar localization mechanism [11].

Other interactions of Khc

• Like para and mle mutations, Khc mutations cause temperature-sensitive (TS) paralysis [20].
• Furthermore, Khc: mutations suppress Shaker and ether-a-go-go mutations that disrupt potassium channel activity [20].
• Furthermore, the KHC localises transiently to the posterior pole in an oskar mRNA-independent manner [7].
• We conclude that most of the actin-rich oocyte cortex can support pole plasm assembly, and propose that Kinesin restricts pole plasm formation to the posterior by moving oskar mRNA away from microtubule-rich lateral and anterior cortical regions [21].
• In addition, germ cells mutant for some milton or Kinesin heavy chain (Khc) alleles transport mitochondria to the oocyte prematurely and excessively, without disturbing Balbiani body-associated components [22].

Analytical, diagnostic and therapeutic context of Khc

• Both negative staining and cryo-electron microscopy revealed a regular pattern of kinesin bound to the microtubule surface, with an axial repeat of 8 nm [23].
• We have used saturation binding and electron microscopy to examine the interaction of the kinesin motor domain with the microtubule surface and found that binding saturated at one kinesin head per tubulin heterodimer [23].
• Sequence analysis of a full-length cDNA encoding KLP68D demonstrates that this protein has a domain that shares significant sequence identity with the entire 340-amin acid kinesin heavy chain motor domain [19].
• Genes encoding these proteins were identified by using the polymerase chain reaction with degenerate primers corresponding to highly conserved regions of the kinesin heavy-chain motor domain [24].
• Minus-end-directed motion of kinesin-coated microspheres driven by microtubule depolymerization [25].

References