Biology subjects

Baker, H. A.

Publications and source records attributed to Baker, H. A..

3 recordsLinked to original sources

bioRxiv2026

BAG6 and RNF126 promote the degradation of cytosolic misfolded proteins that contain buried degron motifs

Missense mutations account for the majority of catalogued human disease-associated variants, and many are predicted to destabilize proteins and promote their degradation. To characterize the pathways responsible for recognizing and clearing such variants, we employed a two-pronged approach to identify both quality control components mediating turnover of misfolded proteins and the sequence elements within their substrates that drive this process. Using a panel of unstable cytosolic missense variants in proximity-labeling and RNAi-based experiments, we identified the BAG6-RNF126 pathway as contributing to the clearance of a subset of these substrates. Applying a tile-based approach to a model cytosolic protein, we uncovered strong potential degrons, including a C-terminal degron degraded in part in a BAG6- and RNF126-dependent manner. Modeling supports that this degron can be accommodated by BAG6. Together, our findings add to the growing body of evidence implicating the BAG6-RNF126 pathway as a key mediator of cytosolic protein quality control.

molecular biology↗

bioRxiv2025

A sensitive orange fluorescent calcium ion indicator for imaging neural activity

Genetically encoded calcium indicators (GECIs) are vital tools for fluorescence-based visualization of neuronal activity with high spatial and temporal resolution. However, current highest-performance GECIs are predominantly green or red fluorescent, limiting multiplexing options and efficient excitation with fixed-wavelength femtosecond lasers operating at 1030 nm. Here, we introduce OCaMP (also known as O-GECO2), an orange fluorescent GECI engineered from O-GECO1 through targeted substitutions to improve calcium affinity while retaining the favorable photophysical properties of mOrange2. OCaMP exhibits improved two-photon cross-section, responsiveness, photostability, and calcium affinity relative to O-GECO1. In cultured neurons, zebrafish, and mouse cortex, OCaMP outperforms the red GECIs jRCaMP1a and jRGECO1a in sensitivity, kinetics, and signal-to-noise ratio. These properties establish OCaMP as a robust tool for high-fidelity neural imaging optimized for 1030 nm excitation and a compromise-free option within the spectral gap between existing green and red GECIs.

neuroscience↗

bioRxiv2024

The co-chaperone DNAJA2 buffers proteasomal degradation of cytosolic proteins with missense mutations

Mutations can result in the loss of a proteins native function due to protein misfolding, which is generally handled by an intricate protein quality control network. To better understand the triaging mechanisms of misfolded cytosolic proteins, we screened a human mutation library to identify a panel of unstable mutations. The degradation of these mutated cytosolic proteins is largely dependent on the ubiquitin proteasome system. Using BioID proximity labelling, we found that the co-chaperones DNAJA1 and DNAJA2 are key interactors of one of the mutated proteins. Notably, the absence of DNAJA2 increases the turnover of the mutant protein but not of the wild-type protein. Our work indicates that missense mutations in cytosolic proteins can promote interactions with molecular chaperones that normally do not occur. Assessment of the broader panel of cytosolic mutant proteins shows that the co-chaperone DNAJA2 exhibits three distinct behaviours: acting to stabilize solely the mutant, both the wild-type and mutant proteins, or being dispensable. Our work illustrates how distinct elements of the protein homeostasis network are utilized in the presence of a cytosolic misfolded protein. Summary StatementWe identified a panel of cytosolic mutant proteins degraded by the proteasome. DNAJA2 is often required to prevent mutant protein turnover, even if it is sometimes dispensable for the wild-type protein.

cell biology↗