Molecular Biology of the Cell: Receptor Digestion and Vesicle Budding

Vocabulary flashcards covering key concepts from the lecture notes on receptor digestion and vesicle budding, including MVBs, endocytosis, and ESCRT complexes.

MVBs (Multivesicular Bodies)

Cellular structures where the formation of internal vesicles is required for complete digestion of endocytosed receptors.

Signal transduction receptors

Receptors whose catalytic end is typically in the cytosolic portion, often targeted for endocytosis when active.

Post-translational modification

A process, such as phosphorylation or ubiquitylation, that targets active molecules for endocytosis.

Endocytosis

The process by which active molecules, often modified post-translationally, are internalized into the cell.

Lysosomal enzymes

Cellular enzymes that must gain access to the catalytic regions of receptor molecules for their eventual degradation.

Lumenal budding

The process of vesicles forming into the early endosome/MVB, facilitating access for lysosomal enzymes to receptor molecules.

ESCRT complexes

A series of cytosolic protein complexes that drive the budding reaction away from the cytoplasm, utilized in MVB vesicle formation and HIV budding.

Mono-ubiquitin tag

An initiating signal on receptor cytosolic domains for inclusion into MVB vesicles, or on viral envelope proteins for HIV, directing them into CCVs.

Topologically equivalent processes

Describes processes like MVB vesicle formation and HIV budding, which use the same machinery and drive budding away from the cytoplasm.

HIV budding

The process where HIV virions shed from the plasma membrane, topologically equivalent to MVB vesicle formation and utilizing ESCRT complexes.

CCVs (Clathrin-Coated Vesicles)

Structures at the plasma membrane into which ubiquitinated receptors are directed prior to their inclusion into MVB vesicles.