Intracellular Compartments and Protein Transport

These flashcards cover essential vocabulary regarding intracellular compartments, protein transport, and associated processes.

Endomembrane system

A network of membranes within the cell, connected directly or via vesicular transport, including the nuclear envelope, ER, Golgi, endosomes, and lysosomes.

Transmembrane proteins

Proteins that are partially translocated across the ER membrane, destined for organelle membranes or the plasma membrane.

ER signal sequence

A sequence of amino acids that directs proteins to the endoplasmic reticulum (ER) for translocation.

Start transfer sequence

A sequence of hydrophobic amino acids that initiates translocation of proteins into the ER.

Stop transfer sequence

An internal sequence within a protein that halts its translocation into the ER.

Vesicular transport

The process by which proteins and lipids are transported in vesicles between different compartments in the cell.

Clathrin

A protein that coats vesicles, helping to shape membranes into vesicles during vesicular transport.

Dynamin

A protein that assembles around the neck of a budding vesicle and employs GTP hydrolysis to facilitate vesicle detachment.

Glycosylation

A post-translational modification involving the attachment of oligosaccharides to proteins, commonly occurring in the ER.

Unfolded protein response (UPR)

A cellular response triggered by the accumulation of misfolded proteins in the ER, aiming to restore proper protein folding or trigger cell apoptosis.

Cisternal maturation model

A model explaining protein trafficking through the Golgi whereby cisternae mature and change as they move through the Golgi stack.

Constitutive exocytosis

A form of exocytosis that occurs continuously to deliver lipids and proteins to the plasma membrane and extracellular matrix.

Regulated exocytosis

A process where vesicles fuse with the plasma membrane and release their contents only upon receiving a specific signal.

Rab proteins

Monomeric GTPases that help direct transport vesicles to their specific target membranes.

SNAREs

Proteins that mediate the fusion of vesicles with target membranes, including v-SNAREs on vesicles and t-SNAREs on target membranes.

Protein quality control

The process by which the ER ensures that only properly folded proteins exit the ER, facilitated by chaperones.

Apoptosis

Programmed cell death, which may be triggered when misfolded proteins accumulate and the UPR fails to correct the issue.

Cargo receptors

Membrane-bound proteins that bind to specific cargo proteins and facilitate their transport in vesicles.

Oligosaccharide

A carbohydrate composed of a small number of monosaccharides, involved in the glycosylation of proteins.

Disulfide bonds

Covalent bonds formed between cysteine residues in proteins that help stabilize their structure.