What do smooth endoplasmic reticulum and rough endoplasmic reticulum have in common?

The smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER) share the characteristic of being continuous with the outer nuclear membrane. This connection allows for efficient transport of proteins and other molecules between the nucleus and the endoplasmic reticulum, facilitating cellular processes and communication.

The rough endoplasmic reticulum is studded with ribosomes that give it a "rough" appearance and is primarily involved in the synthesis of proteins destined for secretion or for use within the cell. In contrast, the smooth endoplasmic reticulum lacks ribosomes and plays a crucial role in lipid synthesis and detoxification processes. Despite their different functions, both types of ER originate from the same membrane system, making them structurally and functionally interconnected.

The connections to the outer nuclear membrane enable the coordinated production and processing of proteins and lipids, which are essential for many cellular functions, but specifically highlights their shared relation to the nuclear envelope.