Protein Synthesis & Secretion Flashcards
Polyribosome
A cluster of ribosomes along a single strand of mRNA having a spiral configuration for synthesizing proteins for intracellular use.
Ribosome
Organelles comprised of small and large subunit, each of which is composed of several molecules of rRNA and proteins. They are either attached to RER or fee in the cytosol which are known as polysomes.
endoplasmic reticulum
Membranous cytoplasmic organelle that may be coated with polysomes (RER) or may lack attached ribosomes (smooth ER)
Rough endoplasmic reticulum
Outer surface studded with ribosomes. Interior region is called the intracisternal space or lumen. Proteins formed are destined to be secreted, plasma membrane proteins, and lysosomal proteins
Smooth ER
Irregular membrane bound tubules, may be continuous with RER but is separate organelle. Prominent in cells synthesizing steroids, triglycerides, and cholesterol. Functions in steroid synthesis, drug detoxification, and the release and recapture of calcium ions for muscle contraction
Co translational insertion
Process of inserting newly formed polypeptide through to pore into RER lumen
Proteosome
Degrades misfolded proteins after they are transported out of the RER
Golgi complex
Organelle consisting of stacked saccules and associated vesicles, functioning in sorting and packaging of cellular products
Cop I
Transports vesicles between Golgi compartments (both anterograde and retrograde)
Cop II
Transports vesicles from TER to CGN (only anterograde)
Clathrin
Transports vesicles from TGN to secretory granules or lysosomes
Constitutive secretion
Default pathway; is more or less continuous and needs no special stimulus. Ex. Secretion of antibodies from an activated plasma cell.
Regulated secretion
Is on demand and stimulus (extracellular signal) is required; ex. Secretion of hormones. Proteins that undergo regulated secretion are found in secretory granules and accumulate near the cell membrane
