Nucleotide sequence of cloned cDNAs encoding human preproparathyroid hormone

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Human preproparathyroid hormone (prePTH) plays a crucial role in calcium homeostasis.
• Previous studies had incomplete or disrupted amino acid sequence data for human prePTH.

Purpose of the Study:

• To clone and sequence the complementary DNA (cDNA) of human preproparathyroid hormone.
• To elucidate the complete amino acid sequence and regulatory regions of human prePTH.

Main Methods:

• Insertion of double-stranded DNA into plasmid pBR322 using the poly(dG) . poly(dC) homopolymer extension technique.
• Identification of recombinant plasmids via filter hybridization with 32P-labeled bovine preproparathyroid cDNA.
• Nucleotide sequence analysis of five recombinant plasmids.

Main Results:

• Assignment of 74 nucleotides in the 5' noncoding region, 345 nucleotides in the coding region, and 348 nucleotides in the 3' noncoding region of the mRNA.
• Prediction of the complete "pre" amino acid sequence and clarification of the mature hormone's sequence.
• Identification of an upstream AUG codon and a UGA stop codon before the authentic initiator codon in the 5' noncoding region.
• Characterization of the 3' noncoding region, finding it 120 nucleotides longer than bovine preproparathyroid mRNA and containing potential polyadenylation signals (A-A-U-A-A-A).

Conclusions:

• The successful cloning and sequencing provide the complete human preproparathyroid hormone sequence.
• The findings clarify the previously disrupted amino acid sequence and reveal novel regulatory elements.