What transports protein round a cell?
I am not sure what you are trying to ask. I think you may be asking about the mechanism used to transport proteins from one point within the cell to another within the cell. If this is the case then the answer would be transport vesicles, free ribosomes, and filaments Transport vesicles move proteins from the rough ER to other areas. Free ribosomes houses newly made proteins from mRNA until the polypeptide chain is complete. Some are then brought to the rough ER. Some proteins are able to move along the filaments. These proteins are used to transport organelles across the cytoplasm.