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Characterization and expression of the complementary DNA encoding rat histidine decarboxylase
D R Joseph1, P M Sullivan, Y M Wang
1Department of Pediatrics, University of North Carolina, Chapel Hill 27599.
Summary
Researchers cloned the L-histidine decarboxylase (HDC) gene from rat liver, revealing its amino acid sequence. This enzyme is crucial for histamine production, impacting neurotransmission and allergic responses.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Histamine is a key neurotransmitter and regulator of physiological processes, including gastric acid secretion, inflammation, and allergic reactions.
- The enzyme L-histidine decarboxylase (HDC) catalyzes histamine synthesis from histidine.
Purpose of the Study:
- To clone the complementary DNA (cDNA) encoding L-histidine decarboxylase (HDC) from a fetal rat liver library.
- To determine the amino acid sequence of HDC and analyze its homology with other decarboxylases.
Main Methods:
- Cloning of HDC-encoding cDNA using a phage lambda gt11 library.
- Deduction of the amino acid sequence from the nucleotide sequence.
- Expression of recombinant HDC in COS cells and chromosomal mapping to confirm clone identity.
Main Results:
- The HDC cDNA encodes a protein of 655 amino acids (Mr 73,450).
- A discrepancy in molecular weight suggests potential post-translational modification of HDC.
- The N-terminal 469 amino acids show 50% identity to rat and Drosophila L-dopa decarboxylases.
Conclusions:
- The study successfully cloned and sequenced HDC cDNA, providing insights into histamine synthesis.
- The findings suggest HDC may undergo post-translational processing.
- Homology analysis indicates a shared evolutionary origin with other amino acid decarboxylases.