A toolbox for systematic discovery of stable and transient protein interactors in baker's yeast.

Identification of both stable and transient interactions is essential for understanding protein function and regulation. While assessing stable interactions is more straightforward, capturing transient ones is challenging. In recent years, sophisticated tools have emerged to improve transient interactor discovery, with many harnessing the power of evolved biotin ligases for proximity labelling.

Systematic analysis of membrane contact sites in uncovers modulators of cellular lipid distribution.

Actively maintained close appositions between organelle membranes, also known as contact sites, enable the efficient transfer of biomolecules between cellular compartments. Several such sites have been described as well as their tethering machineries. Despite these advances we are still far from a comprehensive understanding of the function and regulation of most contact sites.

Cnm1 mediates nucleus-mitochondria contact site formation in response to phospholipid levels.

Mitochondrial functions are tightly regulated by nuclear activity, requiring extensive communication between these organelles. One way by which organelles can communicate is through contact sites, areas of close apposition held together by tethering molecules. While many contacts have been characterized in yeast, the contact between the nucleus and mitochondria was not previously identified.

Interaction mapping of endoplasmic reticulum ubiquitin ligases identifies modulators of innate immune signalling.

Ubiquitin ligases (E3s) embedded in the endoplasmic reticulum (ER) membrane regulate essential cellular activities including protein quality control, calcium flux, and sterol homeostasis. At least 25 different, transmembrane domain (TMD)-containing E3s are predicted to be ER-localised, but for most their organisation and cellular roles remain poorly defined. Using a comparative proteomic workflow, we mapped over 450 protein-protein interactions for 21 stably expressed, full-length E3s.

Double the Fun, Double the Trouble: Paralogs and Homologs Functioning in the Endoplasmic Reticulum.

The evolution of eukaryotic genomes has been propelled by a series of gene duplication events, leading to an expansion in new functions and pathways. While duplicate genes may retain some functional redundancy, it is clear that to survive selection they cannot simply serve as a backup but rather must acquire distinct functions required for cellular processes to work accurately and efficiently. Understanding these differences and characterizing gene-specific functions is complex.

Conserved cytoplasmic domains promote Hrd1 ubiquitin ligase complex formation for ER-associated degradation (ERAD).

The mammalian ubiquitin ligase Hrd1 is the central component of a complex facilitating degradation of misfolded proteins during the ubiquitin-proteasome-dependent process of ER-associated degradation (ERAD). Hrd1 associates with cofactors to execute ERAD, but their roles and how they assemble with Hrd1 are not well understood. Here, we identify crucial cofactor interaction domains within Hrd1 and report a previously unrecognised evolutionarily conserved segment within the intrinsically disordered cytoplasmic domain of Hrd1 (termed the HAF-H domain), which engages complementary segments in the cofactors FAM8A1 and Herp (also known as HERPUD1).