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).

A multi subunit protease complex located in the endoplasmic reticulum membrane that cleaves the signal sequence from precursor proteins following their transport out of the cytoplasmic space.

The formation from simpler components of N-acetylneuraminate, the anion of 5-(acetylamino)-3,5-dideoxy-D-glycero-D-galacto-non-3-ulosonic acid.

The volume enclosed by the membranes of the endoplasmic reticulum.

The chemical reactions involving CMP-N-acetylneuraminate, a substance composed of 5-(acetylamino)-3,5-dideoxy-D-glycero-D-galacto-non-3-ulosonic acid in glycosidic linkage with cytidine monophosphate.

The lipid bilayer surrounding the endoplasmic reticulum.

Catalysis of the reaction: ATP + an acid + CoA = AMP + diphosphate + an acyl-CoA.

A prelysosomal endocytic organelle defined by the time it takes for endocytosed macromolecules to be delivered. The time of delivery may vary ; for example, late endosomes are usually loaded 4-30 min after endocytic uptake in mammalian cells. late endosomes are more spherical than early endosomes and are mostly juxtanuclear, being concentrated near the microtubule organizing center. They are differentiated from early endosomes by their lower lumenal pH and different protein composition.