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Coding sequences for vasoactive intestinal peptide and PHM-27 peptide are located on two adjacent exons in the human
Abstract:
The human precursor gene for vasoactive intestinal peptide (VIP) and PHM-27, a peptide that has an NH2-terminal histidine and COOH-terminal methionine amide and is closely related in sequence and activity to VIP, was detected with synthetic oligodeoxynucleotide probes. These specific hybridization segments were constructed according to the neuroblastoma VIP cDNA sequence and contained up to 39 bases. The gene structure was partly deduced by hybridization to synthetic oligodeoxynucleotide probes and partly by direct chemical nucleotide sequencing. Four exons were discovered thus far; among them are two short exons separated by a 0.75-kilobase DNA stretch, one encoding PHM-27 and the second encoding VIP (exons 1 and 2). Each of these two exons encodes both the hormone amino acid residues as well as the post-translational processing signal sequences. The 3' splice sites of the two exons contain an identical stretch of nine nucleotides. At the cDNA level, the 3' splice sites contain the same stretch of six nucleotides, which are identically spliced. The occurrence of VIP and PHM-27 coding sequences on two separate exons of the human genome and the homology of their 3' splice site may allow alternative RNA processing as discussed below.
Insights
Researchers identified the human gene for vasoactive intestinal peptide (VIP) and PHM-27. These related peptides are encoded on separate exons, suggesting potential alternative RNA processing pathways.
Area of Science:
- Molecular Biology
- Genetics
- Neuroendocrinology
Background:
- Vasoactive intestinal peptide (VIP) is a key neuropeptide involved in various physiological processes.
- PHM-27 is a related peptide with similar sequence and activity to VIP.
- Understanding the genetic basis of these peptides is crucial for neuroendocrine research.
Purpose of the Study:
- To detect and characterize the human precursor gene for VIP and PHM-27.
- To elucidate the gene structure, including exon-intron organization.
- To investigate potential mechanisms for alternative RNA processing.
Main Methods:
- Synthetic oligodeoxynucleotide probes based on neuroblastoma VIP cDNA sequence.
- Hybridization techniques for gene detection and structure analysis.
- Direct chemical nucleotide sequencing for precise gene mapping.
Main Results:
- The human precursor gene for VIP and PHM-27 was successfully detected.
- Four exons were identified; exons 1 and 2 encode PHM-27 and VIP, respectively.
- Identical nine-nucleotide sequences at the 3' splice sites of these two exons were observed.
Conclusions:
- The VIP and PHM-27 coding sequences reside on separate exons within the human genome.
- Homology in the 3' splice sites suggests a mechanism for alternative RNA processing.
- This genetic organization may allow for differential expression and function of VIP and PHM-27.