Identification of a vitamin K-dependent carboxylase in the venom duct of a Conus snail.
Peptides from the venom ducts of cone snails (genus Conus) contain gamma-carboxyglutamate residues. The gamma-glutamyl carboxylase responsible for this post-translational modification is localized in the microsomal fraction, strictly dependent on vitamin K, activated by ammonium sulfate, and is associated with endogenous substrate. The K(m) of the enzyme for vitamin K is comparable to that for the bovine carboxylase. However, a propeptide containing substrate related to the blood coagulation protein factor IX, a highly efficient substrate for the bovine enzyme, was poorly carboxylated by the Conus enzyme, suggesting differences in gamma-carboxylase recognition signal sequences and/or structural requirements at the carboxylation site.
Stanley
T B
TB
Department of Biology, University of North Carolina, Chapel Hill 27599-3280, USA.
Stafford
D W
DW
Olivera
B M
BM
Bandyopadhyay
P K
PK
D015055:1-Carboxyglutamic Acid / Q000096:biosynthesis*; D000818:Animals; D019735:Carbon-Carbon Ligases; D004305:Dose-Response Relationship, Drug; D008025:Ligases / Q000187:drug effects / Q000302:isolation & purification*; D008861:Microsomes / Q000201:enzymology; D008978:Mollusk Venoms / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012908:Snails / Q000201:enzymology*; D013045:Species Specificity; D013379:Substrate Specificity; D014812:Vitamin K / Q000494:pharmacology
D008978:Mollusk Venoms; D014812:Vitamin K; D015055:1-Carboxyglutamic Acid; D008025:Ligases; D019735:Carbon-Carbon Ligases; C020660:glutamyl carboxylase