The answer is: endoplasmic reticulum.
This organelle is composed of membrane-enclosed structures that look like tube or sacs known as cisternae. Its roles are role in the production, processing, and transport of proteins and lipids. There are two forms of endoplasmic reticulum (ER):
• Rough ER-covered with ribosomes which are the side of protein synthesis
• Smooth ER-involved in synthesis of lipids and steroids
From ER, newly formed proteins are transported to lysosomes, Golgi apparatus, plasma membrane…
