Membranes III Protein Targeting- Lecture 8/23/21

Question 1

The signal sequence

Answer 1

If 20 aa hydrophobic sequence is there, directed to the ER for translation, if not, translated in cytoplasma

Question 2

Destination of cytoplasmic translation

Answer 2

Nucleus (needs NLS) Mitochondria, Cytoplasm, Peroxisomes (SKL)

Question 3

NLS

Answer 3

Short basic sequence (KKKRK)

Question 4

Mitochondria import sequence

Answer 4

75 aa sequence because complex organelle with two membranes

Question 5

Peroxisome import sequence

Answer 5

SKL, serine lysine leucine

Question 6

ER return sequence

Answer 6

KDEL, lysine aspartate, glutamate, leucine

Question 7

Chaperone proteins

Answer 7

Bind to proteins when they’re malformed for degradation (ex heat shock) or brings them from one place to another (importins or exportins)

Question 8

Peroxisomes

Answer 8

Small organelle where the reduction of any oxidizing agents occurs, H202

Question 9

Zellweger syndrome

Answer 9

SKL sequence is mutated, can’t import into peroxisomes, die within 3 years

Question 10

Transmembrane proteins

Answer 10

Lodged in the ER membrane via stop signal, make their way to plasma membrane through vesicles transport

Question 11

Cis golgi

Answer 11

Located near the nucleus, In charge of phosphorylation and mannose addition to lysosome proteins

Question 12

Trans golgi

Answer 12

Furthest away, processes and sorts

Question 13

M6P receptor

Answer 13

Binds to lysosomal enzymes in the trans golgi and transports them to lysosome via clathrin coated pits

Question 14

I-cell disease

Answer 14

Defective mannose 6 phosphate transferase, can’t get any lysosomal enzymes in the lysosomes