Endomembrane systems Flashcards
Glycosylation
Addition of carbohydrates to glycoproteins
Sarcoplasmic Reticulum
Located in muscle cells
Smooth ER that specializes in Ca+ storage
Rough ER function
Synthesis of proteins, modification, folding & sorting of proteins
What does the Rough ER synthesize & how?
Secretory proteins
Ribosomes on cytosolic side synthesize membrane-bound and soluble proteins for endomembrane system
What modifications does Rough ER make?
- Initial steps of protein glycosylation
- Assembly of multimeric proteins
What folding & sorting of proteins does Rough ER complete?
- Folding of polypeptides
- recognition and removal of misfolded proteins
- Connects to golgi using tagged vesicles
Functions of Smooth ER
- Drug detoxification
- Ca+ storage
- Carbohydrate metabolism
How are drugs detoxified in Smooth ER?
CYP proteins/ enzymes catalyze the hydroxylation of drugs
How are carbohydrates metabolized in Smooth ER?
Glycogen is broken down using specialized enzyme (6-phosphatase)
Structure of Smooth vs Rough ER
Smooth ER: circular/ tubular structure, no ribosomes
Rough ER: Studded with ribosomes, long, flattened sheets
What does Smooth ER synthesize?
steroid hormones, lipids, membrane lipids
Golgi apparatus
series of flattened cisternae that proteins move through (cis-trans) to be modified, tagged, and transported to final destinations
Cis golgi (CGN)
smallest, outer edge faces nucleus (intake of unfinished proteins)
Trans golgi (TGN)
largest, outer edge faces outside cell (export of final proteins)
Membrane biosynthesis process
Fatty acids synthesized in the cytoplasm are incorporated into the ER membrane on cytosolic side. Flippases flip some lipids to lumenal side to even it out
