Download exam 3 | BIOL 311 - Principles Of Cell Biol (DIS) and more Quizzes Biology in PDF only on Docsity!
co-translational targeting
when cells begin to import most proteins into the ER before synthesis is completeribsosome synthesizing the protein is attached directly to the ER membrane, enabling one end of the protein to be translocated into the ER while the rest of the polypeptide chain is being assembled. These ribosomes coat the ER thus creating the RER. TERM 2
post-translational
DEFINITION 2 synthesis and transport are two separate processes TERM 3
signal recognition particle (SRP)
DEFINITION 3 cycles between the ER membrane and cytosol and binds to the signal sequence and the SRP receptor TERM 4
stop transfer sequence
DEFINITION 4 anchors the protein in the membrane after the ER signal sequence has been released from the trans-locator and has been cleaved off TERM 5
type 1 proteins
DEFINITION 5 hydrophobic stop transfer sequencesignal sequence is cleaved off
type 2 proteins
no signal sequence is cleaved from amino endremains attached to the anchor sequence: signal anchor sequencecarboxylic end in ER lumen, amino end remains in the cytosoltranslocon stays open TERM 7
type 3 proteins
DEFINITION 7 no signal sequence is cleaved from amino endremains attached to the anchor sequence: signal anchor sequenceamino end ends in the ER lumen, carboxylic end in the cytosol TERM 8
type 4 proteins
DEFINITION 8 multi pass proteinsno signal sequence on the amino endhave signal anchor sequence and stop-transfer signal TERM 9
lipid anchor proteins
DEFINITION 9 signal is cleaved on amino endhydrophobic stop-transfer sequenceA GPI transamidase cleaves protein and link it to a GPI anchor in the ER membrane TERM 10
glycosylation
DEFINITION 10 Always driven by an enzyme2 types:Addition of CHO chains to Amide nitrogen of asparagine N-linked glycosylationOH of serine and threonine O-linked glycosylation
calnexin
Membrane bound chaperone protein, only functions by binding to glucose on carbohydrate protein(aka lectin) TERM 17
Bip
DEFINITION 17 chaperone protein that keeps protein linear, binds to amino acid, requires ATP TERM 18
KDEL
DEFINITION 18 signal retrieval sequence, and must bind to its receptor to return back to the ER The pH difference between ER and Golgi tightens the binding of KDEL proteins to receptor to avoid their escape. TERM 19
constitutive pathway
DEFINITION 19 proteins secreted outside the cell as soon as they're formed: Maintenance proteins (ECM proteins) TERM 20
regulated pathway
DEFINITION 20 Proteins are synthesized and stored until needed (hormones)
m6p enzyme tag
in the trans-golgi, where m6p receptors reside. -require a low pH level to work -act in digesting material sent to the lysosomes -when some molecules escape, they are taken back by receptor-mediated endocytosis to the lysosomes TERM 22
i- cell disease
DEFINITION 22 m6p enzyme tag is defective and therefore the cell cannot be taken to the lysosome for digestion, this leads to the build up of cell toxicity -hydrolases cannot go to the lysosome TERM 23
Hurler's disease
DEFINITION 23 enzyme required for the breakdown of certain types of glycosaminoglycan chains is defective or missing -> mental retardation, organ failure TERM 24
Hsc
DEFINITION 24 escorts mitochondrial proteins, keeps them unfolded chaperone protein uses ATP
