protein that makes up the coat of one type of transport vesicle. clathrin-coated vesicles bud from the golgi apparatus on the outward secretory pathway and bud from the plasma membrane on the inward endocytic pathway.
small membrane enclosed organelle with a cage of proteins (the coat) on its cytosolic surface. it is formed by the pinching off of a protein coated region of membrane.
contents of the main compartment of the cytoplasm, excluding membrane enclosed organelles such as endoplasmic reticulum and mitochondria. the cell fraction remaining after membranes, cytoskeletal ccomponents, and other organelles have been removed.
uptake of material into a cell by an invagination of the plasma membrane and its internalization in a membrane-bounded vesicle.
endoplasmic reticulum (ER)
labyrinthine, membrane enclosed compartment in the cytoplasm of eukaryotic cells, where lipids are secreted and membrane bound proteins are made.
membrane enclosed compartment of a eukaryotic cell through which endocytosed material passes on its way to lysosomes.
preocess by which most molecules are secreted from a eukaryotic cell. these molecules are packaged in membrane enclosed vesicles that fuse with the plasma membrane, releasing their contents to the outside.
membrane-enclosed organelle in eukaryotic cells where the proteins and lipids made in the endoplasmic reticulum are modified and sorted for transport to other sites.
intracellular membrane-enclosed organelle containing digestive enzymes, typically those most active at the acid pH found in these organelles.
any organelle in the eukaryotic cell that is surrounded by a lipid bilayer membrane, for example, the endoplasmic reticulum, golgi apparatus, and lysosome.
double membrane surrounding the nucleus. consists of outer and inner membranes perforated by nuclear pores.
channel through the nuclear envelope that allows selected large molecules to move between the nucleus and the cytoplasm.
small membrane-enclosed organelle that uses molecular oxygen to oxidize organic molecules. contains some enzymes that produce hydrogen peroxide (H202) and others that degrade it.
a cell such as a macrophage or neutrophil that is specialized to take up particles and microorganisms by phagocytosis.
the process by which particulate material is engulfed ("eaten") by a cell. prominent in predatory cells, such as Amoeba proteus and in cells of the vertebrate immune system such as macrophages.
type of endocytosis in which soluble materials are taken up from the environment and incorporated into vesicles for digestion. (literally, "cell drinking")
a family of small GTP-binding proteins present on the surfaces of transport vesicles and organelles that serve as molecular markers identifying each membrane type. Rab proteins help to ensure that transport vesicles fuse only with the correct membrane.
mechanism of selective uptake of material by animal cells in which a macromolecule binds to a receptor in the plasma membrane and enters the cell in a clathrin-coated vesicle.
rough endoplasmic reticulum (RER)
region of the endoplasmic reticulum associated with ribosomes and involved in the synthesis of secreted and membrane-bound proteins.
production and release of a substance from a cell.
membrane-enclosed organelle in which molecules destined for secretion are stored prior to release. sometimes calles a secretory granule because darkly staining contents make the organelle visible as a small solid object.
amino acid sequence that directs a protein to a specific location in the cell, such as the nucleus or mitochondria.
one of a family of membrane proteins responsible for the selective fusion of vesicles with a target membrane inside the cell.
membrane vesicles that carry proteins from one intracellular compartment to another, for example from the ER to the golgi apparatus.
unfolded protein response (UPR)
cellular response triggered by the accumulation of misfolded proteins in the endoplasmic reticulum. the cell produces more endoplasmic reticulum and more of the molecular machinery needed to restore proper protein folding and processing.
transport of material between two organelles in the eukaryotic cell via membrane-enclosed vesicles.