A protein interaction map for cell polarity development.
Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein-protein interactions that mediate cell polarity development, and to uncover novel mechanisms that coordinate the numerous events involved, we carried out a large-scale two-hybrid experiment. 68 Gal4 DNA binding domain fusions of yeast proteins associated with the actin cytoskeleton, septins, the secretory apparatus, and Rho-type GTPases were used to screen an array of yeast transformants that express approximately 90% of the predicted Saccharomyces cerevisiae open reading frames as Gal4 activation domain fusions. 191 protein-protein interactions were detected, of which 128 had not been described previously. 44 interactions implicated 20 previously uncharacterized proteins in cell polarity development. Further insights into possible roles of 13 of these proteins were revealed by their multiple two-hybrid interactions and by subcellular localization. Included in the interaction network were associations of Cdc42 and Rho1 pathways with proteins involved in exocytosis, septin organization, actin assembly, microtubule organization, autophagy, cytokinesis, and cell wall synthesis. Other interactions suggested direct connections between Rho1- and Cdc42-regulated pathways; the secretory apparatus and regulators of polarity establishment; actin assembly and the morphogenesis checkpoint; and the exocytic and endocytic machinery. In total, a network of interactions that provide an integrated response of signaling proteins, the cytoskeleton, and organelles to the spatial cues that direct polarity development was revealed.
Drees
B L
BL
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Sundin
B
B
Brazeau
E
E
Caviston
J P
JP
Chen
G C
GC
Guo
W
W
Kozminski
K G
KG
Lau
M W
MW
Moskow
J J
JJ
Tong
A
A
Schenkman
L R
LR
McKenzie
A
A
Brennwald
P
P
Longtine
M
M
Bi
E
E
Chan
C
C
Novick
P
P
Boone
C
C
Pringle
J R
JR
Davis
T N
TN
Fields
S
S
Drubin
D G
DG
D000199:Actins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D016764:Cell Polarity / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018816:Genes, cdc / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D022142:Secretory Vesicles / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D000199:Actins; D001426:Bacterial Proteins; D005656:Fungal Proteins; D008164:Luminescent Proteins; D029701:Saccharomyces cerevisiae Proteins; C054562:yellow fluorescent protein, Bacteria; C051302:RHO1 protein, S cerevisiae; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020741:rho GTP-Binding Proteins