Any substance that is able to transfer an electron to another chemical species.

The material contained within the membrane of a peroxisome; in many cells the matrix contains a crystalloid core largely composed of urate oxidase.

Any substance to which an electron may be transferred.

The irregular network of unit membranes, visible only by electron microscopy, that occurs in the cytoplasm of many eukaryotic cells. The membranes form a complex meshwork of tubular channels, which are often expanded into slitlike cavities called cisternae. The ER takes two forms, rough (or granular), with ribosomes adhering to the outer surface, and smooth (with no ribosomes attached).

Any molecular entity that serves as an electron acceptor and electron donor in an electron transport system.

A translocation complex that constitutes the specific site of protein translocation across the endoplasmic reticulum, which involves the signal recognition particle receptor. Composed of a heterotetramer of alpha, beta, gamma and delta subunits (translocon-associated proteins or TRAPs). In yeast it is a heterotrimeric complex consisting of Sec61p, Sbh1p, and Sss1p. The Sec61 complex functions in cotranslational and posttranslational translocation events.

Any metabolic process involving the breakdown of complex substances into smaller products, including the breakdown of carbon compounds with the liberation of energy for use by the cell or organism.

signal recognition particle receptor complex

A transmembrane heterodimeric protein located in the membrane of the rough endoplasmic reticulum. Both subunits contain GTPase domains with which signal recognition particle interacts. In the presence of GTP and SRP receptor, SRP is released from the ribosome-nascent chain complex.

The breakdown into simpler components of a macromolecule, any large molecule including proteins, nucleic acids and carbohydrates.

signal recognition particle (sensu Eukaryota)

A ribonucleoprotein particle of 325 kDa composed of a 7S (300 nucleotide) RNA molecule and a complex of six different polypeptides. This binds both to the N-terminal signal peptide for proteins destined for the endoplasmic reticulum as they emerge from the large ribosomal subunit and also to the ribosome. This binding arrests further translation thereby preventing the proteins from being released into the cytosol. The SRP-ribosome complex then diffuses to the endoplasmic reticulum where it is bound to the signal recognition particle receptor, which allows resumption of protein synthesis and facilitates the passage of the growing polypeptide chain through the translocon. Through a process involving GTP hydrolysis, the SRP-SRP receptor complex dissociates and SRP returns to the cytosol. Of the six polypeptides of SRP the 54 kDa subunit (SRP54) is the central player. It contains an N-terminal GTPase domain and a C-terminal domain that binds directly to the signal peptide and the SRP RNA. As in, but not restricted to, the eukaryotes (Eukaryota, ncbi_taxonomy_id:2759).