What is the composition of the spliceosome?

The spliceosome is a complex molecular machine responsible for the removal of introns from precursor mRNA (pre-mRNA) and the ligation of exons. It comprises a substantial number of proteins and small nuclear RNAs (snRNAs). The composition of the spliceosome is critical for its function, and option B, which states that it consists of 150 proteins and 5 snRNAs, accurately reflects the known structure of this complex.

The spliceosome is made up of five major snRNAs: U1, U2, U4, U5, and U6. These snRNAs play vital roles in recognizing splice sites and catalyzing the splicing reaction. The large number of proteins associated with the spliceosome reflects the complexity of alternative splicing and the regulation of gene expression. Each of the proteins, which can include various spliceosomal proteins and auxiliary factors, contributes to the proper assembly of the spliceosomal components, facilitating the accurate removal of introns and the joining of exons.

The number of proteins indicates the sophisticated nature of spliceosomal function, allowing for multiple regulatory mechanisms to fine-tune RNA processing. The combination of proteins and snRNAs works synergistically to ensure splicing accuracy, which is crucial for the production of functional m