Transport and Sorting of Proteins

Flashcards from the lecture on Transport and Sorting of Proteins, focusing on key concepts like the endoplasmic reticulum, glycosylation, and the mechanisms of protein localization.

Endoplasmic Reticulum (ER)

An organelle involved in the synthesis and sorting of proteins.

Signal Recognition Particle (SRP)

A ribonucleoprotein that recognizes signal peptides and directs them to the ER.

Cotranslational Translocation

The process of inserting nascent proteins into the ER while they are still being synthesized.

Translocon

A protein complex that facilitates the insertion of polypeptides into the endoplasmic reticulum.

Signal Peptide

A short peptide present at the N-terminus of secretory proteins that directs the protein to the ER.

Glycosylation

The process of adding carbohydrate groups to proteins, which is crucial for their stability and function.

N-linked Glycosylation

A type of glycosylation that attaches carbohydrates to the amino group of asparagine side chains.

O-linked Glycosylation

A type of glycosylation that attaches carbohydrates to hydroxyl groups of serine or threonine side chains.

Disulfide Bonds

Covalent bonds formed between the sulfhydryl groups of cysteine side chains, important for the stability of protein structure.

Unfolded Protein Response (UPR)

A cellular response to the accumulation of misfolded proteins in the ER, aimed at restoring normal function.

Proteasome

A large protein complex that degrades unneeded, damaged, or misfolded proteins in order to maintain cellular function.

ER-associated degradation (ERAD)

The process by which misfolded proteins are exported from the ER to the cytosol for degradation.

Tail-anchored Proteins

Membrane proteins whose C-terminus anchors them to the membrane and do not require a signal peptide for insertion.

Type I Transmembrane Proteins

Proteins with an N-terminal signal peptide and a single transmembrane domain.

GPI Anchors

Glycosylphosphatidylinositol anchors that tether proteins to the cell membrane.