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J Biol Chem, Vol. 275, Issue 19, 14667-14677, May 12, 2000
From the Department of Biochemistry and Molecular Biology,
Louisiana State University Health Sciences Center,
New Orleans, Louisiana 70112
Prohormone convertases 1 (PC1) and 2 (PC2) are
members of a family of subtilisin-like proprotein convertases
responsible for proteolytic maturation of a number of different
prohormones and proneuropeptides. Although sharing more than 50%
homology in their catalytic domains, PC1 and PC2 exhibit differences in
substrate specificity and susceptibility to inhibitors. In addition to
these differences, PC2, unlike PC1 and other members of the family, specifically binds the neuroendocrine protein 7B2. In order to identify
determinants responsible for the specific properties of the PC2
catalytic domain, we compared its primary sequence with that of other
PCs. This allowed us to distinguish a PC2-specific sequence at
positions 242-248. We constructed two PC2 mutants in which residues
242 and 243 and residues 242-248 were replaced with the corresponding
residues of PC1. Studies of in vivo cleavage of
proenkephalin, in vivo production of
Mutations in the Catalytic Domain of Prohormone Convertase 2 Result in Decreased Binding to 7B2 and Loss of Inhibition with 7B2
C-terminal Peptide*
, and
-MSH from
proopiomelanocortin, and in vitro cleavage of a
PC2-specific artificial substrate by mutant PC2s did not reveal
profound alterations. On the other hand, both mutant pro-PC2s exhibited
a considerably reduced ability to bind to 21-kDa 7B2. In addition,
inhibition of mutant PC2-(242-248) by the potent natural inhibitor 7B2
CT peptide was almost completely abolished. Taken together, our results
show that residues 242-248 do not play a significant role in defining
the substrate specificity of PC2 but do contribute greatly to binding
7B2 and are critical for inhibition with the 7B2 CT peptide.
*
This work was supported by National Institutes of Health
Grant DK 49703 (to I. L.).The costs of publication of this
article were defrayed in part by the
payment of page charges. The article must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
Present address: INSERM U36, College de France, Paris 75005, France.
§
Supported by a National Institute on Drug Abuse Research Scientist
Development Award. To whom correspondence should be addressed: Dept. of
Biochemistry and Molecular Biology, Louisiana State University Health
Sciences Center, 1901 Perdido St., New Orleans, LA 70112. Tel.:
504-568-4799; Fax: 504-568-6598; E-mail: ilindb@ Lsumc.edu.
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