Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Enzyme
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Query: EC:3.5.1.52 (
PNGase F
)
1,527
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
An important risk factor for thrombosis is the polymorphism R506Q in
factor V
that causes resistance of factor Va to proteolytic inactivation by activated protein C (APC). To study the potential influence of the carbohydrate moieties of factor Va on its inactivation by APC,
factor V
was subjected to mild deglycosylation (neuraminidase plus
N-glycanase
) under nondenaturing conditions. The APC resistance ratio values (ratio of activated partial thromboplastin time [APTT] clotting times with and without APC) of the treated
factor V
were increased (2.4 to 3.4) as measured in APTT assays. O-glycanase treatment of
factor V
did not change the APC resistance ratio. The procoagulant activity of
factor V
as well as its activation by thrombin was not affected by mild deglycosylation. Treatment of
factor V
with neuraminidase and
N-glycanase
mainly altered the electrophoretic mobility of the factor Va heavy chain, whereas treatment with O-glycanase changed the mobility of the connecting region. This suggests that the removal of the N-linked carbohydrates from the heavy chain of factor Va, which is the substrate for APC, is responsible for the increase in susceptibility to inactivation by APC. Thus, variability in carbohydrate could account for some of the known variability in APC resistance ratios, including the presence of borderline or low APC resistance ratios among patients who lack the R506Q mutation.
...
PMID:The carbohydrate moiety of factor V modulates inactivation by activated protein C. 919 57
Thrombin-activated factor Va exists as two isoforms, factor Va(1) and factor Va(2), which differ in the size of their light chains and their affinity for biological membranes. The heterogeneity of the light chain remained following incubation of factor Va with
N-glycanase
. However, we found that the
factor V
C2 domain, which contains a single potential glycosylation site at Asn-2181, was partially glycosylated when expressed in COS cells. To confirm the structural basis for factor Va(1) and factor Va(2), we mutated Asn-2181 to glutamine (N2181Q) and expressed this mutant using a B domain deletion construct (rHFV des B) in COS cells. Thrombin activation of N2181Q released a light chain with mobility identical to that of factor Va(2) on SDS-PAGE. The functional properties of purified N2181Q were similar to those of factor Va(2) in prothrombinase assays carried out in the presence of limiting concentrations of phosphatidylserine. The binding of human factor Va(1) and factor Va(2) to 75:25 POPC/POPS vesicles was also investigated in equilibrium binding assays using proteins containing a fluorescein-labeled heavy chain. The affinity of human factor Va(2) binding to POPC/POPS vesicles was approximately 3-fold higher than that of factor Va(1). These results indicate that partial glycosylation of
factor V
at asparagine-2181 is the structural basis of the light chain doublet and that the presence of this oligosaccharide reduces the affinity of factor Va for biological membranes.
...
PMID:Partial glycosylation at asparagine-2181 of the second C-type domain of human factor V modulates assembly of the prothrombinase complex. 1047 Dec 96
