Sequence of a cDNA encoding horse growth hormone.

The research article details the isolation and sequencing of a complementary DNA (cDNA) that encodes for the horse growth hormone (ecGH). The sequence shows resemblance to a typical mammalian growth hormone pre-protein, with an untranslated region containing two contiguous polyadenylation signals.

Isolation and Sequencing of cDNA

• The researchers were able to isolate a cDNA that encodes for the horse growth hormone. Complementary DNA (cDNA) is synthesized from an mRNA template in a reaction catalyzed by the enzyme reverse transcriptase and the enzyme DNA polymerase. cDNA is often used in gene cloning or as a probe in the study of gene expression.
• After isolation, the cDNA was then sequenced. DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. This particular DNA sequence encodes for the horse growth hormone (ecGH).

Comparison to Typical Mammalian Growth Hormone Pre-protein

• The scientists found that the cDNA coding sequence is similar to a typical mammalian growth hormone pre-protein. Pre-protein is a term for a protein that contains a signal sequence that directs the protein to its proper cellular location.
• This similarity suggests that the horse growth hormone might operate similarly to other mammalian growth hormones, though additional research would be needed to confirm this.

Untranslated Region and Polyadenylation Signals

• The cDNA sequence contains a 3′ untranslated region of 101 nucleotides. An untranslated region (UTR) is an important part of mRNA, but it does not code for protein. The 3′ UTR is located downstream of the coding sequence and plays roles in the regulation of transcription and translation, mRNA stability and the control of mRNA export from the nucleus.
• This 3′ untranslated region carries two contiguous polyadenylation signals. Polyadenylation signals are sequences in the DNA that signal the addition of a string of adenine bases at the end of a pre-mRNA molecule in the process called polyadenylation. This process is an important part of mRNA processing and plays a key role in the stability, transport and efficiency of translation of mRNA.