Nucleus carries the genetic information for protein synthesis in cells. Therefore, what goes into the nucleus, and what comes out of the nucleus are very precisely controlled incells.
surrounds the nucleus
Nuclear pore complex
- -the numerous holes in the envelope
- -very selective of what passes through
- -energy requiring process to pass
nuclear localization signal (NLS)
- -small region on nucleus
- -goes in and comes out with importin (chaperone)
- -escorts ribosomes and RNA molecules out the nucleus
- -goes back in with its own chaperone
How do the proteins made by ribosomes enter into the ER lumen?
- -ER signal sequence
- -protein is made >
- -protein (cytosol), signal recognition particle, binds to it >
- -docks with ER membrane>
- -allows the ribosome to send the newly madeprotein through a channel into the ER lumen.
What happens to the protein inside ER?
- -gets folded
- -gets glycosylated (a sugar chainadded)
- - passes along the ER until it reaches a place where a ER vesicle buds off.
Where do the vesicles go?
The vesicles released from ER travel through the cytosoltowards Golgi apparatus, and join the cis face of Golgi. The proteins inside the vesicles are released into the Golgi lumen.
What happens to the proteins inside Golgi?
- -tags are attached
- -The tags are mostly short sugar chains, sometimes phosphate groups, or small lipid attachments
- -like zip codes
- -With the help of these tags, receptors on the inner-trans face of the Golgi membrane enclose different proteins into different Golgi transport vesicles.
lysosomes > plasma membrane > ER