Where proteins are assembled?

Answer 1

Proteins are assembled in the cytoplasm (outside the nucleus where DNA is stored in most Eukaryotes) in a molecular machine called the Ribosome. The ribosome is itself partly built up of proteins, and partly (the biggest part) of rRNA. Ribosomes assemble proteins according to instructions coded into the nucleotide sequence of mRNAs (messenger RNAs).

The sequence of nucleotides in mRNA determines the sequence of amino acids in the protein (proteins are folded chains of amino acids). Each three nucleotides in the mRNA chain determines which amino acid to place in one specific position in the amino acid chain that builds up the protein.
The message for proteins synthesis comes from nucleus. mRNA, ribosome, tRNA and enzymes together synthesize proteins. They are further modified by post translational modifications such as glycosylation, acylation and folding process in ER and Golgi.

Answer 2

The message for proteins synthesis comes from nucleus. mRNA, ribosome, tRNA and enzymes together synthesize proteins. They are further modified by post translational modifications such as glycosylation, acylation and folding process in ER and Golgi.