Publications by authors named "Lynnelle Larson"
Endoplasmic reticulum-associated degradation (ERAD) mediates the turnover of short-lived and misfolded proteins in the ER membrane or lumen. In spite of its important role, only subtle growth phenotypes have been associated with defects in ERAD. We have discovered that the ERAD proteins Ubc7 (Qri8), Cue1, and Doa10 (Ssm4) are required for growth of yeast that express high levels of the sterol biosynthetic enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR).
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- Increased levels of HMG-CoA reductase promote the growth of the endoplasmic reticulum, specifically forming structures called karmellae in yeast.
- Researchers investigated the genes needed for karmellae assembly by studying 1,557 deletion mutants of S. cerevisiae over 20 generations, identifying 120 potential mutants across three experiments.
- Only two genes, UBC7 and YAL011W, were consistently found across all experiments, indicating a link between HMG-CoA reductase sensitivity and certain mutations, particularly those affecting chromatin and transcription regulation, suggesting karmellae assembly involves transcriptional changes.
In yeast, increased levels of the sterol biosynthetic enzyme, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase isozyme, Hmg1p, induce assembly of nuclear-associated ER membranes called karmellae. To identify additional genes involved in karmellae assembly, we screened temperature-sensitive mutants for karmellae assembly defects. Two independently isolated, temperature-sensitive strains that were also defective for karmellae biogenesis carried mutations in VPS16, a gene involved in vacuolar protein sorting.
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- Increased expression of specific ER membrane proteins can create new ER membrane structures, known as karmellae, in yeast, which helps researchers study how cells manage the size and organization of organelles.
- Discovery by Cox and colleagues showed that the assembly of these karmellae is harmful to yeast cells lacking the ire1 gene, which is crucial for responding to protein folding stress.
- Investigations revealed that ire1 mutants can still form normal karmellae structures, indicating that their death might be more related to their inability to metabolize galactose rather than the presence of karmellae themselves.