Polysome

A polysome, also known as a polyribosome, is a complex of mRNA (messenger RNA) and multiple ribosomes that act in protein synthesis. The structure of a polysome allows for the simultaneous translation of a single mRNA sequence by several ribosomes concurrently. This process enhances the efficiency of protein synthesis.

Structure and Function

Polysomes are composed of a single strand of mRNA and two or more ribosomes. The ribosomes move along the mRNA strand, translating the genetic code into a protein sequence. This process is known as translation. The number of ribosomes on a single mRNA strand can vary, and the entire complex can be visualized using an electron microscope.

The function of polysomes is to synthesize proteins. The multiple ribosomes on a single mRNA strand allow for the simultaneous translation of the same genetic sequence. This increases the efficiency of protein synthesis, allowing for the rapid production of proteins in the cell.

Formation

Polysomes form during the process of translation. When a ribosome begins translating an mRNA strand, another ribosome can attach to the same strand and begin translation as well. This results in the formation of a polysome. The formation of polysomes is regulated by various factors, including the availability of ribosomes and the rate of translation.

Clinical Significance

Polysomes have been implicated in various diseases, including cancer and neurodegenerative diseases. In cancer, polysomes can be overactive, leading to the overproduction of proteins that promote cell growth and division. In neurodegenerative diseases, polysomes can be dysfunctional, leading to the production of misfolded proteins that can damage neurons.

See Also

• Protein biosynthesis
• Translation (biology)
• Ribosome
• Messenger RNA

References

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