What is the second basic step in gene expression?
translation of mRNAs into protein
where does translation occur?
cytoplasm
what occurs after cytoplasmic ribosomal complexes have synthesized a protein?
the functional capabilities of the protein are implemented after the protein has been modified.
what can post-transitional modifications include?
the removal of a part of the translated sequence or the covalent addition of one or more chemical groups required for protein activity
proteins destined for secretion from the cell are initially made as
large, precursor molecules, not functional
What occurs to result in an active molecule?
portions of the protein chain are removed by endoproteases
Where does phosphorylation occur on a protein?
hydroxyl groups of serine, threonine, tyrosine (not as frequent)
phosphorylation may-
increase of decrease the functional activity of the protein.
proteins that are made to be a part of a plasma membrane or lysosome, or to be secreted from the cell have-?
carbohydrate chains attached to serine or threonine hydroxyl groups (o-linked) or the amide nitrogen of asparagine (n-linked)
where does the addition of sugars take place?
ER and golgi
glycosylation can be used to?
target the proteins to specific organelles
What is hydroxylation?
process of adding a hydroxyl group to a protein
Which amino acids are commonly hydroxylated?
proline and lysine (in the ER)
What is carboxylation?
addition of carboxyl group to a protein
What is biotinylation?
addition of biotin to a protein
Biotin is bound to sigma amino groups of lysine residues of-
enzymes that depend on biotin to catalyze carboxylation reactions (ex: pyruvate carboxylase)
Attachment of _____________ can help anchor proteins in membranes
lipids (farnesyl groups)
acetylation is when-
acetyl groups are added to a protein (after translation)