BIO 201 Lecture Notes - Lecture 39: Signal Recognition Particle, Signal Peptide, Protein Targeting

• School: University at Buffalo
• Department: Biological Sciences
• Course: BIO 201
• Professor: Lara Hutson

Document Summary

Observation: a sequence with these characteristics is coded for by mrnas of many secreted proteins. This (cid:862)peptide(cid:863) is not present in mature protein. Experiment 1: remove nt sequence encoding signal peptide from mrna for a normally-secreted protein and express in cells. Result: protein is not secreted signal peptide is necessary for protein secretion. Experiment 2: add nt sequence encoding signal peptide to mrna for a protein that is not normally secreted and express in cells. Result: protein is secreted signal peptide is sufficient for protein secretion. Co-translation import: signal peptide (i. e. signal sequence) binds to signal recognition particle (srp, srp binds to srp receptor on the rer, polypeptide translocate through channel into rer. Hypothesis: this se(cid:395)ue(cid:374)(cid:272)e is a (cid:862)(cid:374)u(cid:272)lea(cid:396) lo(cid:272)alizatio(cid:374) sig(cid:374)al(cid:863) (cid:894)nl (cid:895) (cid:396)espo(cid:374)si(cid:271)le fo(cid:396) targeting proteins to the nucleus. Experiment: re(cid:373)ove (cid:862)nl (cid:863) f(cid:396)o(cid:373) a p(cid:396)otei(cid:374) (cid:374)o(cid:396)(cid:373)ally fou(cid:374)d i(cid:374) the (cid:374)u(cid:272)leus. I(cid:374)je(cid:272)t i(cid:374)to (cid:272)ells a(cid:374)d o(cid:271)se(cid:396)ve: e(cid:374)gi(cid:374)ee(cid:396) (cid:862)nl (cid:863) i(cid:374)to a p(cid:396)otei(cid:374) that is (cid:374)o(cid:396)(cid:373)ally (cid:272)ytoplas(cid:373)i(cid:272).