The complete sequence of human preprocalcitonin

Area of Science:

• Molecular Biology
• Genetics
• Endocrinology

Background:

• Medullary thyroid carcinoma (MCT) is a calcitonin-producing tumor.
• Understanding the molecular basis of MCT requires characterizing calcitonin precursors.

Purpose of the Study:

• To clone and sequence the complementary DNA (cDNA) encoding human preprocalcitonin.
• To deduce the complete amino acid sequence of human preprocalcitonin.

Main Methods:

• Extraction of mRNA from thyroid carcinoma tissue.
• Construction of a recombinant plasmid containing cDNA insert using G-C tailing.
• Transformation of Escherichia coli and screening of ampicillin-resistant clones.
• Hybridization screening using radiolabeled probes and in vitro translation.
• DNA sequencing of positive clones.

Main Results:

• A cDNA insert of 426 bp encoding the entire coding region was isolated.
• The insert contained 70 bp at the 5'-end and 295 bp upstream of the poly(A) tail.
• Restriction sites were compatible with previously published rat calcitonin mRNA sequences.
• The complete amino acid sequence of human preprocalcitonin was deduced.

Conclusions:

• The study successfully cloned and sequenced the full-length cDNA for human preprocalcitonin.
• This provides the complete amino acid sequence, crucial for understanding MCT pathogenesis.
• The findings facilitate further research into calcitonin biology and related disorders.