RNA translation in eukaryotes

The molecular mechanism of translation in eukaryotes is very similar to that in bacteria. The activation of amino acids and attachment to tRNAs and the steps of initiation, elongation, and termination of polypeptide chains are essentially the same in overall terms. The small and large ribosomal subunits of bacteria and eukaryotes are equivalent with respect to their roles in initiation and elongation of chains. 

Most polypeptides synthesized on ribosomes are later chemically modified. Thus the formyl group on the N-terminal methionine in polypeptides of bacteria is removed by a deformylase. In both bacteria and eukaryotes, the N-terminal methionine, sometimes along with a few additional amino acids, is removed by aminopeptidases. 

Question The amino acids hydroxyproline and hydroxylysine are absent from Table 17.1, which describes the genetic code. How do these amino acids arise in some proteins  

Hydroxyproline and hydroxylysine occur most noticeably in collagen. These are formed by modification of proline and lysine residues by specific enzymes after synthesis of the collagen chains. It is interesting to note that proly/hydroxylase, which hydroxylates proline, requires ascorbate (vitamin C) as a coreactant. Other chemical modifications known to occur commonly are the attachment of sugars (glycosylation) to asparagine, serine, and threonine residues and the phosphorylation of serine. Chemical modifications are also associated with the transport of proteins out of the cells in which they are synthesized. 

Question How can proteins be transported through a hydrophobic membrane and out of a cell  

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