Consider two proteins- a transcription factor (nuclear protein) and a hormone receptor (membrane-spanning protein).
Protein 1: transcription factor NH3--------------------------------COO-
Protein 2: Hormone Receptor NH3-------------------------------- COO-
a) What is the difference between protein localization sequences in proteins 1 and 2 such that they are targeted to different cell compartments?
b) Indicate where you would expect to find proteins 1 and 2 in a cell that has a mutated signal recognition particle (SRP). Explain why proteins would be found in these locations.
c) Indicate the correct sequence of events that will lead to the proper localization of proteins 1 and 2.
1.Protein synthesis is blocked by SRP
2.After removal of signal sequence, growing polypeptide enters ER
3.Glycosylation occurs
4.Protein is anchored in plasma membrane
5.Translation of polypeptide chain starts in the cytoplasm on the ribosome
6.Protein synthesis resumes
7.Protein is transported to Golgi in a vesicle
8.SRP attaches to a specific receptor on the ER
9.Growing polypeptide becomes embedded in ER membrane.
10.Vesicle harboring protein buds off Golgi
11.Protein enters nucleus
12.Signal sequence is removed
13.SRP binds signal sequence
14.Vesicle fuses with the plasma membrane
15.Signal sequence binds to receptor on nucleus opening channel
PROTEIN 1: Write correct sequence of event here for Nuclear protein here (for example 1,5,15.......)
PROTEIN 2:Write correct sequence of event here for Hormon receptor protein here (for example 1,5,15.......)
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