W2 ER + Golgi

Question 1

ER structure + function

Answer 1

Continuous w/nuclear envelope
Continuous network of membrane tubules
Protein synthesis, glycosylation (attachment of sugars to proteins), folding, assembly + multi-protein complexes
Lipid synthesis (CL, phospholipid)
Ca2+ sequestration (binding/confining) - storage + 2nd messenger (Ca2+ needed for activation of some PKCs along w/second messenger)
Contains cytochrome P450 enzymes (integral membrane proteins) - detox (most phase I reactions, phase I = making compound more Hphilic by adding OH or other Hphilic group), also used for conversion of pro drugs into active drugs

Question 2

Pancreatic acinar cells

Answer 2

Exocrine (cells that produce/secrete onto epithelial surface) cells’ cytoplasm w/RER
Acinus = round cluster of exocrine cells connected to a duct

Question 3

Co-translational protein targeting to ER

Answer 3

SRP (signal recognition particle) guides RS on top of peptide translocation complex on ER membrane + docked
Peptide threaded into lumen + cleaved by signal peptidase
N-linked glycosylation structural component added to PP in RER + involved in first steps of protein folding

Question 4

Co-translational modification

Answer 4

Covalently altering one/more AAs in protein after translation has begun but before protein released from RS

Question 5

Insulin (pre to mature)

Answer 5

PP insulin 110AA after co-t → SS cleaved off
Now 86 AA of P insulin → proteolysis cuts C peptide out
Now 2 separate peptides covalently linked w/two disulfide bonds (one bond intraM) (A chain 21 AA + B chain 30 AA)

Question 6

Golgi functions

Answer 6

Glycosidases (catalyze hydrolysis of GSD bonds), glycotransferases (catalyze transfer of parts saccharide molecules from glycosyl donor to a nucleophilic glycosyl acceptor)
O-linked glycosylation = attachment of sugar to oxygen in an AA in a protein
Sulfatases = catalyze hydrolysis of sulfate esters of complex macromolecules
Proteases = hydrolysis of proteins
Lipid synthesis = sphingomyelin (synthesized in cis golgi), glucosylceramide (synthesized at cytosolic surface of various golgi subfractions)

Question 7

Proteins + lipids sorted into…

Answer 7

Secretory granules
Plasma membrane
Basolateral versus apical membrane
Endosomes
Lysosomes