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The human growth hormone locus: nucleotide sequence, biology, and evolution
E Y Chen1, Y C Liao, D H Smith
1Department of Molecular and Developmental Biology, Genentech, Inc., South San Francisco, California 94080.
Genomics
|May 1, 1989
Summary
The human growth hormone gene locus, containing five highly similar genes, was fully sequenced. Gene expression analysis revealed pituitary-specific transcription for one gene and placental-specific for the others, highlighting tissue-specific regulation.
Area of Science:
- Genomics
- Molecular Biology
- Evolutionary Biology
Background:
- The human genome contains a locus for growth hormone (GH) and related genes.
- Understanding the structure and regulation of this locus is crucial for comprehending GH and placental hormone biology and evolution.
Purpose of the Study:
- To fully sequence the human chromosomal growth hormone locus.
- To analyze the evolutionary history and gene duplication events within the locus.
- To investigate the tissue-specific expression patterns of the genes within the locus.
Main Methods:
- Whole-genome sequencing of the human growth hormone locus (~66,500 bp).
- Bioinformatic analysis to identify repetitive elements (Alu, KpnI).
- Screening of pituitary and placental cDNA libraries using gene-specific oligonucleotides to assess gene expression.
Main Results:
- The locus contains five highly homologous genes (approx. 95% sequence identity).
- 48 Alu and 1 KpnI repetitive elements were identified in intergenic regions.
- hGH-N gene is pituitary-specific; hCS-L, hCS-A, hGH-V, hCS-B genes are placental-specific.
- A mutation in the hCS-L gene leads to altered splicing and a novel mRNA/polypeptide sequence.
Conclusions:
- The growth hormone locus evolved through gene duplication, resulting in highly similar gene sequences.
- Tissue-specific regulatory elements likely control the differential expression of these genes.
- The hCS-L gene's unique splicing pattern contributes to its distinct function.