Manufacture and secretion of proteins

This is how proteins are manufactured and secreted in cells.

Amino acids pass through the plasma membrane by diffusion down a concentration gradient or by active transport. They then combine with their specific tRNA. They are then transported to ribosomes attached to the rough endoplasmic reticulum, where they are incorporated into a polypeptide via protein synthesis. The protein molecule is then packaged into a transport vesicle, which pinches off from the rough endoplasmic reticulum. The vesicle transports the protein molecule to the Golgi apparatus where it fuses wiht the cis face of the Golgi apparatus. Protein is chemically modified as it moves through the Golgi apparatus, undergoing post-translational modification. Trans face gives rise to vesicles containing the inactive form of the protein. The secretory vesicle eventually buds off from the secreting face of the Golgi apparatus. When vesicles reach the cell surface, it fuses with the plasma membrane, and releases the inactive protein by exocytosis, using ATP in the process.