spliceosomekomplekset

The spliceosome is a large and dynamic molecular machine found within the nucleus of eukaryotic cells. It is responsible for the crucial process of pre-mRNA splicing. Pre-messenger RNA (pre-mRNA) is the initial transcript produced from a gene during transcription. This pre-mRNA contains both coding regions called exons and non-coding regions called introns. For a functional messenger RNA (mRNA) to be produced, the introns must be removed and the exons must be joined together.

The spliceosome is composed of small nuclear ribonucleoproteins (snRNPs), which are complexes of small nuclear RNAs (snRNAs) and associated proteins. The major spliceosome, the most common type, consists of five snRNPs: U1, U2, U4, U5, and U6. These snRNPs, along with numerous auxiliary proteins, assemble on the pre-mRNA in a step-wise manner to form the functional spliceosome.

The process of splicing is highly regulated and involves precise recognition of specific sequences at the boundaries of introns and exons. The spliceosome catalyzes the removal of introns and the ligation of exons through a series of transesterification reactions. This process ensures that only the coding sequences are present in the mature mRNA, which is then translated into protein. Variations in splicing patterns, known as alternative splicing, can generate multiple different proteins from a single gene, significantly increasing the proteomic diversity of an organism. Dysfunctional spliceosomes are implicated in a variety of human diseases, highlighting the vital role of this complex machinery in cellular health.