This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Inside every cell, thousands of proteins must reach the right place at the right time. Helping coordinate this complex logistics network are centriolar satellites—tiny, membraneless organelles that play important roles in protein trafficking, cell division and the formation of cilia.
Despite their importance and links to developmental and neurological disorders, the molecular mechanisms through which centriolar satellites assemble and acquire their functions have remained poorly understood. Elif Nur Fırat-Karalar from Koç University's Department of Molecular Biology and Genetics and School of Medicine reveals that centriolar satellites form through a highly ordered, hierarchical process rather than through the random aggregation of proteins. The findings were published in the Journal of Cell Biology.
The researchers found that centriolar satellite formation begins when a protein called pericentriolar material 1, or PCM1, assembles into a scaffold-like structure. This initial scaffold then recruits other centriolar satellite proteins, known as clients, in a defined sequence. To observe this process, the team developed new cellular and in vitro experimental systems that allowed them to follow centriolar satellite biogenesis over time.
These tools revealed distinct stages of assembly, remodeling and maintenance. The experiments showed that PCM1 can intrinsically form granules through multimerization—the binding of multiple PCM1 molecules to one another. This process is regulated by the cytoskeleton and by proteins associated with ciliary diseases.
The results indicate that PCM1 serves as the core organizing scaffold upon which centriolar satellites are built. High-resolution imaging revealed that centriolar satellites are not structurally uniform. PCM1 and the proteins it recruits occupy distinct subdomains within the organelle, each with different compositions and dynamic properties.
This spatial organization suggests that centriolar satellites have a considerably more sophisticated internal architecture than previously recognized. Rather than functioning simply as passive storage sites, they appear to be active organizational hubs that coordinate the positioning, storage and transport of proteins within the cell. The researchers also showed that PCM1 alone was sufficient to form an internally organized scaffold, selectively recruit specific proteins and interact with microtubules, which form part of the cell's internal transport system.
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