 RNA splicing , carried out by a complex called the <unk> , is the process by which introns , or regions of DNA that do not code for protein , are removed from the pre @-@ mRNA and the remaining exons connected to re @-@ form a single continuous molecule . This process normally occurs after 5 ' capping and 3 ' <unk> but can begin before synthesis is complete in transcripts with many exons . Many pre @-@ <unk> , including those encoding antibodies , can be <unk> in multiple ways to produce different mature <unk> that encode different protein sequences . This process is known as alternative splicing , and allows production of a large variety of proteins from a limited amount of DNA . 
