signal peptide - (Dec/24/2014 )

Now if protein is to be exported out of the cell what type of signal peptides is it supposed to have ? it is obvious that it has in ER importation signal but does it have a signal to direct it to the Golgi or does this process happen by default ? so my question is if a protein only has an importation signal to the ER where would we expect to find this protein ? ( outside the cell ? )

thanks for your help

Hi,

There's no specific GA signal. Proteins that are either secreted or transmembrane have a signal peptide that directs the synthesis to the ER as opposed to synthesis on free cytosolic ribosomes for intracellular proteins. The vesicles with the newly synthesised proteins then migrate from the ER to the GA and onwards to the plasma membrane in a directed fashion.

The wikipedia entry for this is quite detailed: https://en.wikipedia.org/wiki/Signal_peptide

thanks for your help