Mouse stefins A1 and A2 (Stfa1 and Stfa2) differentiate between papain-like endo- and exopeptidases.
Stefin A (Stfa) acts as a competitive inhibitor of intracellular papain-like cysteine proteases which play important roles in normal cellular functions such as general protein turnover, antigen processing and ovarian follicular growth and maturation. In the mouse there are at least three different variants of Stfa (Stfa1, Stfa2 and Stfa3). Recent genetic studies identified structural polymorphisms in Stfa1 and Stfa2 as candidates for Aod1b, a locus controlling susceptibility to day three thymectomy (D3Tx)-induced autoimmune ovarian disease (AOD). To evaluate the functional significance of these polymorphisms, recombinant allelic proteins were expressed in Escherichia coli, purified and characterized. The polymorphisms do not markedly alter the folding characteristics of the two proteins. Stfa1 and Stfa2 both act as fast and tight binding inhibitors of endopeptidases papain and cathepsins L and S, however their interaction with exopeptidases cathepsins B, C and H was several orders of magnitude weaker compared to human, porcine and bovine Stfa. Notwithstanding, the K(i) values for the interactions of Stfa1-b from AOD resistant C57BL/6J mice was 10-fold higher than that of the Stfa1-a allele from susceptible A/J mice for papain, cathepsins B, C and H but not L and S. In contrast, the inhibitory activities of Stfa2-a and Stfa2-b were found to be roughly equivalent for all targets peptidases.
Mihelic
Marko
M
Department of Biochemistry and Molecular Biology, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
Teuscher
Cory
C
Turk
Vito
V
Turk
Dusan
D
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D002417:Cattle; D055312:Cystatin A; D055313:Cystatin B; D015891:Cystatins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010450:Endopeptidases / Q000737:chemistry*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010049:Ovarian Diseases / Q000235:genetics / Q000378:metabolism; D006080:Ovarian Follicle / Q000254:growth & development; D011110:Polymorphism, Genetic; D011480:Protease Inhibitors / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D040641:Quantitative Trait Loci; D013045:Species Specificity; D013552:Swine
C524994:CSTB protein, human; C524992:Cstb protein, mouse; D055312:Cystatin A; D015891:Cystatins; D011480:Protease Inhibitors; C524995:Stfa1 protein, mouse; C524996:Stfa2 protein, mouse; C524998:Stfa3 protein, mouse; D055313:Cystatin B; D010450:Endopeptidases