The site for protein synthesis is
Ribosomes
is the site for protein synthesis. The synthesis of proteins start
with the binding of the ribosome on the rough endoplasmic
reticulum at the translocon. A ribosome only binds to the RER
once a specific protein-nucleic acid complex forms in the cytosol.
This special complex forms when a free ribosome begins translating
the mRNA of a protein destined for the secretory pathway. The first
5-30 amino acids polymerized encode a signal peptide, a molecular
message that is recognized and bound by a signal recognition
particle. So, the correct answer is 'Ribosome'.