Flashcards in Kapitel 13 Deck (64)
Hydrolytic enzymes—including proteases - nucleases - glycosidases - lipases - phospholipases - phosphatases - and sulfatases—that work best at acidic pH; these enzymes are found within the lysosome.
General term for a protein that functions solely to link two or more different proteins together in an intracellular signaling pathway or protein complex. (Figures 13–9 and 15–10)
Monomeric GTPase in the Ras superfamily responsible for regulating both COPI coat assembly and clathrin coat assembly. (Table 15–5 - p. 854)
Organelle surrounded by a double membrane contains engulfed cytoplasmic cargo in the initial stages of autophagy.
Digestion of cytoplasm and worn-out organelles by the cell’s own lysosomes.
The membrane components and soluble molecules carried by transport vesicles.
Invaginations at the cell surface that bud off internally to form pinocytic vesicles. Thought to form from lipid rafts - regions of membrane rich in certain lipids.
caveola (plural caveolae)
Family of unusual integral membrane proteins that are the major structural proteins in caveolae -
Face on the same or near side.
Network of fused vesicular tubular clusters that is closely associated with the cis face of the Golgi apparatus and is the compartment at which proteins and lipids enter the Golgi.
cis Golgi network (CGN)
One hypothesis for how the Golgi apparatus achieves and maintains its polarized structure and how molecules move from one cisterna to another. This model views the cisternae as dynamic structures that mature from early to late by acquiring and then losing speciﬁc Golgi-resident proteins as they move through the Golgi stack with cargo.
cisternal maturation model
Protein that assembles into a polyhedral cage on the cytosolic side of a membrane so as to form a clathrin-coated pit - which buds off by endocytosis to form an intracellular clathrin-coated vesicle. (Figure 13–6)
Specialized regions typically occupying about 2% of the total plasma membrane area at which the endocytic pathway often begins.
Coated vesicles that transport material from the plasma membrane and between endosomal and Golgi compartments.
Members of a family of monomeric GTPases that have important roles in vesicle transport - being responsible for coat assembly at the membrane.
Small membrane-enclosed organelle with a cage of proteins (the coat) on its cytosolic surface. Formed by the pinching off of a coated region of membrane (coated pit). Some coats are made of clathrin - others are made from other proteins.
Broad class of N-linked oligosaccharides - attached to mammalian glycoproteins in the endoplasmic reticulum and modified in the Golgi apparatus - containing N-acetylglucosamine - galactose - sialic acid - and fucose residues.
Pathway present in all cells by which molecules such as plasma membrane proteins are continually delivered to the plasma membrane from the Golgi apparatus in vesicles that fuse with the plasma membrane. The default route to the plasma membrane if no other sorting signals are present. (Figure 13–63)
constitutive secretory pathway
Coated vesicles that transport material early in the secretory pathway - budding from Golgi compartments.
Coated vesicles that transport material early in the secretory pathway - budding from the endoplasmic reticulum.
The transport pathway of proteins directly to the cell surface via the nonselective constitutive secretory pathway - entry into which does not require a particular signal.
Cytosolic GTPase that binds to the neck of a clathrin-coated vesicle in the process of budding from the membrane - and which is involved in completing vesicle formation.
Common receiving compartment with which most endocytic vesicles fuse and where internalized cargo is sorted either for return to the plasma membrane or for degradation by inclusion in a late endosome.
Vesicle formed as material ingested by the cell during endocytosis is progressively enclosed by a small portion of the plasma membrane - which first invaginates and then pinches off to form the vesicle.
Uptake of material into a cell by an invagination of the plasma membrane and its internalization in a membrane-enclosed vesicle. See also pinocytosis and phagocytosis.
Process by which early endosomes mature to late endosomes and endolysosomes; in the conversion process - the endosome membrane protein composition changes - the endosome moves from the cell periphery to close to the nucleus - and the endosome ceases to recycle material to the plasma membrane and irreversibly commits its remaining contents to degradation.
Four protein complexes (ESCRT-0 - ESCRT-1 - ESCRT-2 - and ESCRT-3) that act sequentially to shepherd mono-ubiquitylated membrane proteins on endosomal membranes into intralumenal vesicles. ESCRT-3 complex catalyzes the pinching-off reaction.
ESCRT protein complexes
Excretion of material from the cell by vesicle fusion with the plasma membrane; can occur constitutive or be regulated.
Complex organelle in eukaryotic cells - centered on a stack of flattened - membrane-enclosed spaces - in which proteins and lipids transferred from the endoplasmic reticulum are modified and sorted. It is the site of synthesis of many cell wall polysaccharides in plants and extracellular matrix glycosaminoglycans in animal cells. (Figure 13–26)
Golgi apparatus (Golgi complex)