In human cells, only a small proportion of the information written in genes is used to produce proteins. How does the cell select this information? A large molecular machine called the spliceosome continuously separates the coding and non-coding regions of our genes – and it’s doing this even as you read these lines.
The spliceosome is critical for the proper functioning of every cell, and numerous genetic disorders are linked to problems with spliceosome function. In most eukaryotic cells, two types of spliceosome work in parallel to stitch gene pieces together: the major spliceosome and the minor spliceosome.
The Galej Group at EMBL Grenoble has recently published new structural insights into minor spliceosome function in the journal Molecular Cell.
The major spliceosome is abundant in cells and has been extensively investigated for more than four decades. Its long-separated twin – the minor spliceosome, is much more scarce and remains enigmatic, even though its function is equally important. In this new study, the researchers reveal the structure of U11 snRNP – one of the five subunits of the minor spliceosome, which initiates the intron selection process.
Stitching gene pieces together
Spliceosomes help cells remove large chunks of non-coding genetic information – called introns – from the precursors of messenger RNA (pre-mRNA), the molecule responsible for transferring genetic information from DNA into proteins. Spliceosomes act as an editing tool, helping to make sense of the fragmented messages stored in pre-mRNA.
Most genes have many introns that belong to one class –