@article {5048,
	title = {Cdc4p, a contractile ring protein essential for cytokinesis in Schizosaccharomyces pombe, interacts with a phosphatidylinositol 4-kinase},
	journal = {Journal of Biological Chemistry},
	volume = {276},
	number = {8},
	year = {2001},
	note = {ISI Document Delivery No.: 404RUTimes Cited: 27Cited Reference Count: 35},
	month = {Feb},
	pages = {5932-5942},
	type = {Article},
	abstract = {The proposed function of Cdc4p, an essential contractile ring protein in Schizosaccharomyces pombe, is that of a myosin essential light chain. However, five conditionally lethal cdc4 alleles exhibit complementation in diploids. Such interallelic complementation is not readily explained if the sole function of Cde4p is that of a myosin essential light chain. Complementation of cdc4 alleles could occur only if different mutant forms can assemble into an active oligomeric complex or if Cdc4p has more than one essential function. To search for other proteins that may interact with Cdc4p, we performed a two-hybrid screen and identified two such candidates: one similar to Saccharomyces cerevisiae Vps27p and the other a putative phosphatidylinositol (PI) 4-kinase. finding of Cdc4p to the latter and to myosin heavy chain (Myo2p) was confirmed by immunosorbent assays. Deletion studies demonstrated interaction between the Cdc4p C-terminal domain and the PI 4-kinase C-terminal domain. Furthermore, interaction was abolished by the Cdc4p C-terminal domain point mutation, Gly(107) to Ser. This allele also causes failure of cytokinesis. Ectopic expression of the PI 4-kinase C-terminal domain caused cytokinesis defects that were most extreme in cells carrying the G107S allele. We suggest that Cdc4p plays multiple roles in cytokinesis and that interaction with a PI I-kinase may be important for contractile ring assembly and/or function.},
	keywords = {ACTOMYOSIN RING, BINDING, CELL-DIVISION CYCLE, F-ACTIN, FISSION YEAST, GENE, IDENTIFICATION, LIGHT-CHAIN, LOCALIZATION, MYOSIN HEAVY-CHAIN},
	isbn = {0021-9258},
	url = {<Go to ISI>://000167115100071},
	author = {Desautels, M. and Den Haese, J. P. and Slupsky, C. M. and McIntosh, L. P. and Hemmingsen, S. M.}
}
@article {5199,
	title = {Structure of Cdc4p, a contractile ring protein essential for cytokinesis in Schizosaccharomyces pombe},
	journal = {Journal of Biological Chemistry},
	volume = {276},
	number = {8},
	year = {2001},
	note = {ISI Document Delivery No.: 404RUTimes Cited: 16Cited Reference Count: 49},
	month = {Feb},
	pages = {5943-5951},
	type = {Article},
	abstract = {The Schizosaccharomyces pombe Cdc4 protein is required for the formation and function of the contractile ring, presumably acting as a myosin light chain. By using NMR spectroscopy, we demonstrate that purified Cdc4p is a monomeric protein with two structurally independent domains, each exhibiting a fold reminiscent of the EF-hand class of calcium-binding proteins. Although Cdc4p has one potentially functional calcium-binding site, it does not bind calcium in vitro. Three variants of Cdc4p containing single point mutations responsible for temperature-sensitive arrest of the cell cycle at cytokinesis (Gly-19 to Glu, Gly-82 to Asp, and Gly-107 to Ser) were also characterized by NMR and circular dichroism spectroscopy. In each case, the amino acid substitution only leads to small perturbations in the conformation of the protein. Furthermore, thermal unfolding studies indicate that, like wild-type Cdc4p, the three mutant forms are all extremely stable, remaining completely folded at temperatures significantly above those causing failure of cytokinesis in intact cells. Therefore, the altered phenotype must arise directly from a disruption of the function of Cdc4p rather than indirectly through a disruption of its overall structure. Several mutant alleles of Cdc4p also show interallelic complementation in diploid cells. This phenomenon can be explained if Cdcp4 has more than one essential function or, alternatively, if two mutant proteins assemble to form a functional complex. Based on the structure of Cdc4p, possible models for interallelic complementation including interactions with partner proteins and the formation of a myosin complex with Cdc4p fulfilling the role of both an essential and regulatory light chain are proposed.},
	keywords = {BINDING PROTEINS, CALCIUM-SATURATED STATES, ESSENTIAL LIGHT-CHAIN, FISSION YEAST, MYOSIN HEAVY-CHAIN, NUCLEAR-MAGNETIC-RESONANCE, REGULATORY DOMAIN, SCALLOP MYOSIN, TARGETED DISRUPTION, TROPONIN-C},
	isbn = {0021-9258},
	url = {<Go to ISI>://000167115100072},
	author = {Slupsky, C. M. and Desautels, M. and Huebert, T. and Zhao, R. H. and Hemmingsen, S. M. and McIntosh, L. P.}
}
