Ice2p is important for the distribution and structure of the cortical ER network in Saccharomyces cerevisiae

Abstract

In Saccharomyces cerevisiae, the endoplasmic reticulum (ER) is found along the cell periphery (cortical ER) and nucleus (perinuclear ER). In this study, we characterize a novel ER protein called Ice2p that localizes to the cortical and perinuclear ER. Ice2p is predicted to be a type-III transmembrane protein. Cells carrying a genomic disruption of ICE2 display defects in the distribution of cortical ER in mother and daughter cells. Furthermore, fluorescence imaging of ice2Δ cells reveals an abnormal cortical ER tubular network morphology in both the mother cell and the developing bud. Subcellular fractionation analysis using sucrose gradients corroborate the data from the fluorescence studies. Our findings indicate that Ice2p plays a role in forming and/or maintaining the cortical ER network in budding yeast.

A 3D analysis of yeast ER structure reveals how ER domains are organized by membrane curvature

“…We used our 3D models to define the organization of the ER during early stages of ER inheritance. ER tubules are inherited first into the bud, initially along the mother–bud axis as previously suggested (Du and Novick, 2001; Estrada de Martin et al, 2005b). Our work additionally reveals that the source of the inherited ER is from the mother cecER and tubER domains and not from the pmaER.…”

ER-associated retrograde SNAREs and the Dsl1 complex mediate an alternative, Sey1p-independent homotypic ER fusion pathway

“…Among the 22 dsl1 ΔE-specific negative interactions ( Table 1 ), eight were related to trafficking (although not exclusively retrograde trafficking), and seven were related to transcriptional regulation. The final seven interactions consist of sey1 Δ, whose dsl1 ΔE-specific negative interaction ( Figure 1B ) motivated the genome-wide screen; ice2 Δ, a gene involved in inheritance of cortical ER ( Estrada de Martin et al , 2005 ) that also has a negative genetic interaction with sey1 Δ ( Figure 2B ); act1-2 , an actin allele; pyc2 Δ, a pyruvate carboxylase isoform; atg15 Δ, a lipase involved in autophagy; and two dubious open reading frames (ORFs), ygr139w Δ and ypr050c Δ. Of note, although act1-2 displayed the strongest negative genetic interaction, 19 other act1 alleles tested displayed no genetic interaction.…”

Genome-Wide Functional Profiling Identifies Genes and Processes Important for Zinc-Limited Growth of Saccharomyces cerevisiae

“…ICE2 was previously identified as being needed for proper ER morphology [33]. Ice2 is an integral membrane protein with eight potential transmembrane domains suggesting that it is a transporter of some type.…”