centrosomeSPB

The centrosome is a key organelle in animal cells and some lower plants and fungi, responsible for organizing microtubules. In the yeast Saccharomyces cerevisiae, the analogous structure is called the spindle pole body (SPB). While functionally similar in their role as microtubule organizing centers (MTOCs) during cell division, the centrosome and SPB have distinct structural compositions and origins.

The centrosome is characterized by a pair of centrioles, which are cylindrical structures made of microtubules. These centrioles are surrounded by pericentriolar material (PCM), which contains proteins essential for nucleating microtubules. Centrosomes duplicate during the cell cycle and mature into the spindle poles that organize the mitotic spindle.

The SPB, in contrast, lacks centrioles. It is a multilayered structure embedded in the nuclear envelope of yeast cells. The SPB also contains proteins that nucleate microtubules and plays a crucial role in forming the spindle. During mitosis, the SPB duplicates and moves to opposite sides of the nucleus, organizing the microtubules that separate chromosomes. Despite these structural differences, both the centrosome and SPB are essential for accurate chromosome segregation and cell division. Research on both structures contributes to our understanding of cell cycle control and the mechanisms of microtubule organization.