Endóplasmatískum

Endóplasmatískum, more commonly known as the endoplasmic reticulum or ER, is a complex network of membranes found within eukaryotic cells. It is composed of flattened sacs called cisternae and interconnected tubules. The ER plays a crucial role in the synthesis, modification, and transport of proteins and lipids. It is continuous with the outer nuclear membrane and extends throughout the cytoplasm of the cell.

There are two distinct regions of the endoplasmic reticulum: the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER). The RER is studded with ribosomes on its surface, giving it a "rough" appearance. These ribosomes are responsible for synthesizing proteins that are destined for secretion, insertion into membranes, or delivery to other organelles. Within the RER lumen, newly synthesized proteins undergo folding and modification, such as glycosylation.

The SER lacks ribosomes and appears "smooth." Its functions are more diverse and include lipid synthesis, detoxification of drugs and poisons, and calcium storage. In muscle cells, the SER is specialized as the sarcoplasmic reticulum and plays a vital role in muscle contraction by regulating calcium ion concentration. The ER is a dynamic organelle, constantly remodeling its structure and interacting with other cellular components. Its integrity and proper functioning are essential for cell survival and overall organismal health. Disruptions in ER function are implicated in various diseases.