Two similar but nonallelic rat pancreatic trypsinogens. Nucleotide sequences of the cloned cDNAs.

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Abstract

We have cloned and identified mRNA sequences for two rat pancreatic trypsinogens. Nucleotide sequence analysis of the cloned sequences revealed two mRNAs that encode similar, though noallelic, pretrypsinogens. Trypsinogen I mRNA is 804 nucleotides in length, plus an estimated poly(A) tract of 100 nucleotides, and contains a short (13 nucleotide) 5' noncoding region and a 3' noncoding region of 54 nucleotides. It encodes a preproenzyme of 246 amino acids comprising a hydrophobic prepeptide (signal peptide) of 15 amino acids, an activation peptide characteristic of trypsinogens, and an active form of trypsin, 223 amino acids in length, that has 78% amino acid sequence identity with porcine trypsin. Trypsinogen II mRNA has a nucleotide sequence 88% homologous with that of trypsinogen I mRNA and encodes a protein with 89% amino acid sequence identity with trypsinogen I. The enzymes encoded by trypsinogen I and II mRNAs retain the key amino acid residues that determine the characteristic substrate cleavage preference of trypsins and, therefore, represent the rat counterparts of this digestive enzyme. Trypsinogen I mRNA is a major pancreatic mRNA comprising an estimated 2-5% of the total, whereas trypsinogen II mRNA is present at much lower levels.

Original languageEnglish (US)
Pages (from-to)9724-9732
Number of pages9
JournalJournal of Biological Chemistry
Volume257
Issue number16
StatePublished - Aug 25 1982

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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