- As the modification processes continue
in the granules, protein ages in the granules. It has been found
that the freshest, most biologically active, protein is secreted first
if an impulse to exocytose the granules is received: last made = first
Transcription of nuclear gene, including
introns and exons, into heteronuclear mRNA
Excision of introns and modification of
the transcript by capping of the 5' end and addition of the poly-A tail
to the 3' end to generate mature mRNA.
Binding of mRNA to ribosomes on the endoplasmic
Translation of mRNA into precursor protein,
often with a leader sequence that inserts through the ER membrane with
the help of a docking protein.
Clipping of the leader sequence, protein
folding, and formation of -S-S- bridges.
Movement to the Golgi Apparatus where carbohydrate
additions and modifications occur.
Movement up the Golgi stack toward the
plasma membrane as limited proteolysis, further protein folding and condensation
occur (e.g., multimer formation)
Packaging of the proteins in granules ready