Definition of Initiation
Initiation is the step in the process of transcription (converting the DNA strand into mRNA) that involves the binding of an enzyme i.e. RNA polymerase to the promoter region of the DNA strand which basically tells the polymerase to begin transcribing. The promoter region is composed of DNA sequences and every gene has its own defined promoter. In this way, it is known to be the first step that begins the synthesis of RNA. The RNA polymerase synthesizes the new strand of RNA from the DNA template in the 5’ to 3’ direction.
Several other enzymes come and play their role in transcription the DNA strand. The transcription process is increased when an inducer comes and gets attached to the template. On the contrary, the process of transcription is inhibited by small effector molecules that get attached to the activator protein. These molecules are known as inhibitors and they cause the protein to be released from the DNA strand. These inhibitors can be used as antibiotics and antifungals.
The initiation can also be defined in terms of the translation process which involves the formation of a complex between the messenger RNA, the initiator RNA, and the subunits of ribosomes. The Initiator tRNA is responsible for recognizing the start codon that is present in the mRNA. Its structure plays a pivotal role in the process and it binds directly with the peptidyl (P) site of the ribosomal subunit.