Related Experiment Videos
Sequence homology between human alpha 1-antichymotrypsin, alpha 1-antitrypsin, and antithrombin III
Abstract:
alpha 1-Antichymotrypsin mRNA was isolated by specific polysome immunoprecipitation from turpentine-treated baboon liver. The highly enriched mRNA was used for synthesis and cloning of the corresponding cDNA. Baboon alpha 1-antichymotrypsin cDNA clones were identified by hybrid-selected translation, and the insert DNA fragment from one of the putative clones was used as a probe to screen a human liver cDNA library comprised of 40 000 independent transformants. One of the human cDNA clones was unambiguously identified to contain alpha 1-antichymotrypsin DNA sequences by comparison of its 5'-terminal nucleotide sequence with the N-terminal amino acid sequence of the protein. This cDNA clone, designated phACT235, contains 1524 base pairs of human DNA, which was sequenced in its entirety. The inserted DNA codes for a 25 amino acid signal peptide sequence and the entire mature alpha 1-antichymotrypsin of 408 amino acid residues. Comparison of the amino acid sequence of alpha 1-antichymotrypsin with that of the human alpha 1-antitrypsin has revealed a homology level similar to that between chymotrypsin and trypsin.
Insights
Researchers isolated alpha 1-antichymotrypsin mRNA from baboon liver to synthesize and clone its complementary DNA (cDNA). This led to the identification and sequencing of a human alpha 1-antichymotrypsin cDNA clone, phACT235.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Alpha 1-antichymotrypsin is a key protease inhibitor.
- Understanding its genetic basis is crucial for studying related diseases.
Purpose of the Study:
- To isolate and characterize the complementary DNA (cDNA) for alpha 1-antichymotrypsin.
- To enable further studies on alpha 1-antichymotrypsin gene expression and function.
Main Methods:
- Specific polysome immunoprecipitation for mRNA isolation from turpentine-treated baboon liver.
- cDNA synthesis, cloning, and hybrid-selected translation for baboon alpha 1-antichymotrypsin identification.
- Screening of a human liver cDNA library and DNA sequencing of the identified clone (phACT235).
Main Results:
- Successfully synthesized and cloned baboon alpha 1-antichymotrypsin cDNA.
- Identified and sequenced a human alpha 1-antichymotrypsin cDNA clone (phACT235) of 1524 base pairs.
- The human cDNA sequence codes for a 25 amino acid signal peptide and the mature protein of 408 amino acids.
Conclusions:
- The study provides the complete DNA sequence for human alpha 1-antichymotrypsin.
- The deduced amino acid sequence shows significant homology to human alpha 1-antitrypsin, suggesting shared evolutionary origins and functional similarities.