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Pancreas‐specific genes: Structure and expression
Author(s) -
Macdonald Raymond J.,
Crerar Michael M.,
Swain William F.,
Pictet Raymond L.,
Rutter William J.
Publication year - 1981
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/1097-0142(19810315)47:6+<1497::aid-cncr2820471410>3.0.co;2-a
Subject(s) - coding region , biology , microbiology and biotechnology , untranslated region , messenger rna , nucleic acid sequence , gene , base pair , genomic dna , genetics
Via recombinant DNA technology the mRNA sequence of pancreatic amylase has been cloned and its nucleotide sequence has been determined. The cloned sequence represents 96% of the total length of amylase mRNA; missing are an estimated 75 ± 30 nucleotides from the 5′ end. The amino acid sequence of rat pancreatic amylase was deduced solely from the nucleotide sequence of the mRNA. Unlike other eukaryotic mRNAs, the amylase mRNA has short 5′ and 3′ untranslated regions, suggesting that long untranslated regions of eukaryotic mRNAs either do not contain extensive functional sequences or that these sequences are incorporated within the amino acid coding region of amylase mRNA. The cloned amylase mRNA sequence was radiolabeled and used as a probe for in situ hybridization. These experiments demonstrate that amylase mRNA is present in all acinar cells but not in other pancreatic cell types. Using the cloned amylase mRNA sequences as a hybridization probe, three nonoverlapping genomic DNA fragments containing amylase gene sequences were isolated. From the similar sequence organization of the three amylase genes visualized by DNA heteroduplex mapping, a consensus structure of a rat amylase gene is proposed. It is an extended gene structure 10 kilobase pairs in length containing the 1547 base pairs of the cloned mRNA coding sequence interrupted by seven intervening sequences ranging from 400–2000 base pairs long. Thus, in nuclear DNA the amylase mRNA coding sequence is disrupted into at least eight segments from 150–300 base pairs long.