Project description:Cotranslational targeting into the endoplasmic reticulum (ER) by the Signal Recognition Particle (SRP) is a key event determining polypeptide fate in eukaryotic cells. Here, we globally define the principles and mechanisms of SRP binding and ER targeting in vivo. Cotranslational targeting through SRP is the dominant route into the ER for all secretory proteins, regardless of targeting signal characteristics. Cytosolic SRP functions in a pioneer translation round that builds a membrane-resident mRNAs pool, explaining how low SRP levels suffice for the secretory load. SRP does not induce an elongation arrest; consequently, kinetic competition between targeting and translation elongation dictates which substrates are translocated post-translationally. Unexpectedly, SRP binds most secretory ribosomal complexes before targeting signals are synthesized. We show non-coding mRNA elements can promote signal-independent SRP pre-recruitment. Our study defines the complex kinetic interplay between elongation and determinants in the polypeptide and mRNA modulating SRP-substrate selection and membrane targeting in vivo. Ribosome profiling (RiboSeq) and RNA-seq of subcellular fractions of ribosomes. Soluble and membrane bound ribosomes are separated by centrifugation, and SRP-bound ribosomes are immunoprecipitated from the soluble fraction. Polysomes and monosomes are separated by sucrose gradient ultracentrifugation.

2016-08-03 | E-GEOD-74393 | biostudies-arrayexpress

Outer membrane protein size and LPS O-antigen define protective antibody targeting to the Salmonella surface.

Project description: Not available

| S-EPMC7015928 | biostudies-literature

Postsynaptic Targeting and Mobility of Membrane Surface-Localized hASIC1a.

Project description: Not available

| S-EPMC7870742 | biostudies-literature

J-domain proteins promote client relay from Hsp70 during tail-anchored membrane protein targeting.

Project description: Not available

| S-EPMC8054193 | biostudies-literature

SRP orchestrates protein biogenesis beyond initial ER-membrane targeting

Project description:The Signal Recognition Particle (SRP) is crucial for targeting nascent proteins to the endoplasmic reticulum (ER). However, its range of substrates and point of engagement during targeting, and hence full biological impact remain unclear. Here, we examined SRP interactions with the nascent proteome of S. cerevisiae during translation and membrane targeting. SRP binds effectively to transmembrane domains (TMDs) as they emerge from the ribosomal tunnel, but not to most cleavable signal peptides. We identify nascent chain features that promote SRP binding, allowing to develop a predictive algorithm. We show SRP performs a role in triaging nascent ER proteins into distinct targeting routes and downstream maturation processes. Furthermore, ribosomes frequently dissociate from the membrane before completing translocation, allowing the chaperone Ssb to assist folding of emerging cytosolic domains. Ribosomes translating multipass membrane proteins are retargeted through repeated SRP interactions with internal TMDs, emphasizing collaboration between SRP and chaperones in membrane protein biogenesis.

2026-05-13 | GSE295216 | GEO

The spatio-temporal dynamics of mitochondrial membrane potential during oocyte maturation.

Project description: Not available

| S-EPMC6884418 | biostudies-literature