Cellular integrity in @entity375 is ensured by a rigid cell wall whose synthesis is controlled by a MAP kinase signal transduction cascade. In @entity375 upstream regulatory components of this MAP kinase pathway involve a single protein kinase C, which is regulated in part by interaction with the small GTPase @entity34214 . This small G protein is in turn rendered inactive ( @entity3006 -bound) or is activated ( @entity3007 -bound) by the influence of GTPase activating proteins (GAPs) and the @entity3006 / @entity3007 exchange factors (GEFs), respectively. We report here on the isolation of a gene from @entity11900 , KlROM2, which encodes a member of the latter protein family. The @entity377 sequence contains an open reading frame of 1227 @entity1522 , with an overall identity of 57% to the @entity70349 protein of @entity375 . Four conserved sequence motifs could be identified: a RhoGEF domain, a DEP sequence, a CNH domain and a less conserved pleckstrin homology (PH) sequence. Klrom2 null mutants show a lethal phenotype, which indicates that the gene may encode the only functional GEF regulating the cellular integrity pathway in @entity11900 . Conditional genomic expression of KlROM2 resulted in sensitivity towards caffeine and Calcofluor white as typical phenotypes of mutants defective in this pathway. Overexpression of KIROM2 from multicopy plasmids under the control of the ScGAL1 promoter severely impaired growth in both @entity375 and in @entity11900 . The fact that the lethal phenotype was not prevented in mpk1 deletion mutants indicates that growth inhibition is not simply caused by hyperactivation of the Pkc1p signal transduction pathway.

KlROM2 encodes an essential GEF homologue in XXXX .

@entity3007 :: ('MESH:D006160', 'Chemical') :: ['GTP'] @entity1522 :: ('CHEBI:33709', 'Chemical') :: ['amino acids'] @entity377 :: ('CHEBI:36976', 'Chemical') :: ['nucleotide'] @entity34214 :: ('856294(Tax:4932)', 'Gene') :: ['Rho1p'] @entity3006 :: ('MESH:D006153', 'Chemical') :: ['GDP'] @entity11900 :: ('28985', 'Species') :: ['Kluyveromyces lactis', 'K. lactis'] @entity375 :: ('4932', 'Species') :: ['S. cerevisiae', 'Saccharomyces cerevisiae', 'yeasts'] @entity70349 :: ('851086(Tax:4932)', 'Gene') :: ['Rom2']
@entity11900 :: (28985,Species) :: ['Kluyveromyces lactis']
