Prohormone convertase 2 enzymatic activity and its regulation in neuro-endocrine cells and tissues.
We used the fluorometric substrate, pGlu-Arg-Thr-Lys-Arg-MCA and the C-terminal peptide of human 7B2(155-185), a specific inhibitor of prohormone convertase 2 (PC2), to specifically measure the enzymatic activity of the prohormone convertases, PC2. Using lysates from the pancreatic alpha cell line, alphaTC1-6 cells, which contain moderate levels of PC2 enzymatic activity, we determined that the PC2 assay was linear with respect to time of incubation and protein added and had a pH optimum of 5.5 and a calcium optimum of 2.5 mM. Rat pituitary contained high levels of PC2 enzymatic activity, while the hypothalamus and other brain regions contained moderate levels. This enzyme assay was used to document that both mice null for PC2 as well as mice null for the PC2 cofactor, 7B2, had only trace levels of PC2 activity in various brain regions, while mice heterozygous for these alleles had approximately half of the PC2 activity in most brain regions. PC2 enzymatic activity and PC2 mRNA levels were somewhat discordant suggesting that PC2 mRNA levels do not always reflect PC2 enzymatic activity.
Li
Qiao-Ling
QL
Division of Endocrinology, Charles R. Drew University of Medicine and Sciences, UCLA School of Medicine, 1731 E. 120th Street, Los Angeles, CA 90059, USA.
Naqvi
Syed
S
Shen
Xiaoxiong
X
Liu
Yan-Jun
YJ
Lindberg
Iris
I
Friedman
Theodore C
TC
D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000166:cytology / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004702:Endocrine Glands / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006863:Hydrogen-Ion Concentration; D051379:Mice; D018345:Mice, Knockout; D045706:Proprotein Convertase 2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats
D012333:RNA, Messenger; D045706:Proprotein Convertase 2; D002118:Calcium