scholarly journals Pea2 protein of yeast is localized to sites of polarized growth and is required for efficient mating and bipolar budding.

1996 ◽  
Vol 135 (3) ◽  
pp. 725-739 ◽  
Author(s):  
N Valtz ◽  
I Herskowitz
Keyword(s):  
Coiled Coil ◽  
Cell Types ◽  
Cell Polarization ◽  
Polarized Growth ◽  
Coiled Coil Domain ◽  
Cell Biol ◽  
Two Phases ◽  
Diploid Cells ◽  
Novel Protein

Saccharomyces cerevisiae exhibits polarized growth during two phases of its life cycle, budding and mating. The site for polarization during vegetative growth is determined genetically: a and alpha haploid cells exhibit an axial budding pattern, and a/alpha diploid cells exhibit a bipolar pattern. During mating, each cell polarizes towards its partner to ensure efficient mating. SPA2 is required for the bipolar budding pattern (Snyder. M 1989. J. Cell Biol. 108:1419-1429; Zahner, J.A., H.A. Harkins, and J.R. Pringle. 1996. Mol. Cell. Biol. 16:1857-1870) and polarization during mating (Snyder, M., S. Gehrung, and B.D. Page. 1991. J. Cell Biol. 114: 515-532). We previously identified mutants defective in PEA2 and SPA2 which alter cell polarization in the presence of mating pheromone in a similar manner (Chenevert, J., N. Valtz, and I. Herskowitz. 1994. Genetics, 136:1287-1297). Here we report the further characterization of these mutants. We have found that PEA2 is also required for the bipolar budding pattern and that it encodes a novel protein with a predicted coiled-coil domain. Pea2p is expressed in all cell types and is localized to sites of polarized growth in budding and mating cells in a pattern similar to Spa2p, Pea2p and Spa2p exhibit interdependent localization: Spa2p is produced in pea2 mutants but fails to localize properly; Pea2p is not stably produced in spa2 mutants. These results suggest that Pea2p and Spa2p function together as a complex to generate the bipolar budding pattern and to guarantee proper polarization during mating.

scholarly journals The Vfl1 Protein in Chlamydomonas Localizes in a Rotationally Asymmetric Pattern at the Distal Ends of the Basal Bodies

2001 ◽  
Vol 153 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Carolyn D. Silflow ◽  
Matthew LaVoie ◽  
Lai-Wa Tam ◽  
Susan Tousey ◽  
Mark Sanders ◽  
...  
Keyword(s):  
Basal Body ◽  
Rotational Symmetry ◽  
Coiled Coil ◽  
Mutant Phenotype ◽  
Basal Bodies ◽  
Repeat Sequences ◽  
Coiled Coil Domain ◽  
Cell Biol ◽  
Asymmetric Pattern ◽  
Rotational Orientation

In the unicellular alga Chlamydomonas, two anterior flagella are positioned with 180° rotational symmetry, such that the flagella beat with the effective strokes in opposite directions (Hoops, H.J., and G.B. Witman. 1983. J. Cell Biol. 97:902–908). The vfl1 mutation results in variable numbers and positioning of flagella and basal bodies (Adams, G.M.W., R.L. Wright, and J.W. Jarvik. 1985. J. Cell Biol. 100:955–964). Using a tagged allele, we cloned the VFL1 gene that encodes a protein of 128 kD with five leucine-rich repeat sequences near the NH2 terminus and a large α-helical–coiled coil domain at the COOH terminus. An epitope-tagged gene construct rescued the mutant phenotype and expressed a tagged protein (Vfl1p) that copurified with basal body flagellar apparatuses. Immunofluorescence experiments showed that Vfl1p localized with basal bodies and probasal bodies. Immunogold labeling localized Vfl1p inside the lumen of the basal body at the distal end. Distribution of gold particles was rotationally asymmetric, with most particles located near the doublet microtubules that face the opposite basal body. The mutant phenotype, together with the localization results, suggest that Vfl1p plays a role in establishing the correct rotational orientation of basal bodies. Vfl1p is the first reported molecular marker of the rotational asymmetry inherent to basal bodies.

Fa1p is a 171 kDa protein essential for axonemal microtubule severing in Chlamydomonas

2000 ◽  
Vol 113 (11) ◽  
pp. 1963-1971 ◽  
Author(s):  
R.J. Finst ◽  
P.J. Kim ◽  
E.R. Griffis ◽  
L.M. Quarmby
Keyword(s):  
Coiled Coil ◽  
Subcellular Fractionation ◽  
Rt Pcr ◽  
Type Locus ◽  
Microtubule Severing ◽  
Calmodulin Binding ◽  
Amino Terminal ◽  
Binding Domains ◽  
Coiled Coil Domain ◽  
Novel Protein

A key event in deflagellation or deciliation is the severing of the nine outer-doublet axonemal microtubules at a specific site in the flagellar transition zone. Previous genetic analysis revealed three genes that are essential for deflagellation in Chlamydomonas. We have now identified the first of these products, Fa1p, a protein required for Ca(2+)-dependent, axonemal microtubule severing. Genetic mapping and the availability of a tagged allele allowed us to physically map the gene to the centromere-proximal domain of the mating-type locus. We identified clones of Chlamydomonas genomic DNA that rescued the Ca(2+)-dependent axonemal microtubule severing defect of fa1 mutants. The FA1 cDNA, obtained by RT-PCR, encodes a novel protein of 171 kDa, which is predicted to contain an amino-terminal coiled-coil domain and three Ca(2+)/calmodulin binding domains. By western analysis and subcellular fractionation, the FA1 product is enriched in flagellar-basal body complexes. Based on these observations and previous studies, we hypothesize that a Ca(2+)-activated, Ca(2+)-binding protein binds Fa1p leading ultimately to the activation of axonemal microtubule severing.

scholarly journals Transmembrane and Coiled-Coil Domain Family 1 Is a Novel Protein of the Endoplasmic Reticulum

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e85206 ◽  
Author(s):  
Chao Zhang ◽  
Yik-Shing Kho ◽  
Zhe Wang ◽  
Yan Ting Chiang ◽  
Gary K. H. Ng ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coiled Coil ◽  
Domain Family ◽  
Coiled Coil Domain ◽  
Novel Protein

scholarly journals A combined characterization of coelomic fluid cell types in the spiny starfish Marthasterias glacialis – inputs from flow cytometry and imaging

2020 ◽  
Author(s):  
Bárbara Oliveira ◽  
Silvia Guatelli ◽  
Pedro Martinez ◽  
Beatriz Simões ◽  
Claúdia Bispo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Cell Viability ◽  
Cell Types ◽  
Coelomic Fluid ◽  
Transmission Electron ◽  
Marthasterias Glacialis ◽  
Combined Microscopy ◽  
Diploid Cells

ABSTRACTCoelomocytes is a generic name for a collection of cellular morphotypes, present in many coelomate animals, that has been reported as highly variable across echinoderm classes. The roles attributed to the major types of the free circulating cells present in the coelomic fluid of echinoderms include immune response, phagocytic digestion and clotting. The main aim of the present study is the thorough characterization of coelomocytes present in the coelomic fluid of Marthasterias glacialis (class Asteroidea) through the combined use of flow cytometry (FC) and fluorescence plus transmission electron microscopy. Two coelomocyte populations (here named P1 and P2) were identified by flow cytometry and subsequently studied in terms of abundance, morphology, ultrastructure, cell viability and cell cycle profiles. Ultrastructurally, P2 diploid cells showed two main morphotypes, similar to phagocytes and vertebrate thrombocytes, whereas the small P1 haploid cellular population was characterized by a low mitotic activity, relatively undifferentiated cytotype and a high nucleus/cytoplasm ratio. These last cells resemble stem-cell types present in other animals. P1 and P2 cells differ also in cell viability and cell cycle profiles. Additionally, two other morphotypes were only detected by fluorescence microscopy and a third one when using a combined microscopy/FC approach.

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