Kinetic studies on Korean serum cis-AB enzymes reveal diminished A and B transferase activities.
BACKGROUND
cis-AB enzymes are rare glycosyltransferases that synthesize both blood group A and B antigens. We have identified a large cohort of Korean cis-AB blood donors and studied the N-acetylgalactosaminyltransferase (glycosyltransferase A, GTA) and galactosyltransferase (glycosyltransferase B, GTB) activity of their cis-AB serum enzymes.


METHODS
The cis-AB01 allele was identified by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) in 60 donors collected at the Gwangju-Chonnam Red Cross Blood Center. Enzyme assays of this cis-AB enzyme were performed on available serum samples from 16 donors with the cis-AB01/O genotype and three with the cis-AB01/A genotype.


RESULTS
In cis-AB donors with an O allele, both the GTA and GTB activity of the cis-AB enzyme were markedly reduced compared to normal A and B controls (29% and 27%, respectively). This is consistent with the behaviour predicted from kinetic studies of a recombinant model of the corresponding AAAB enzyme.


CONCLUSIONS
Although variable, cis-AB enzymes feature reduced GTA and GTB activities.


CONCLUSIONS
Cis-AB enzymes feature variable but reduced GTA and GTB activities with relatively weaker GTB activity, consistent with the weak agglutination present on forward typing with anti-B.
Yazer
M H
MH
The Institute for Transfusion Medicine and Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA. myazer@itxm.org
Zheng
R B
RB
Seto
N O L
NO
Rose
N L
NL
Cho
D
D
Palcic
M M
MM
D000017:ABO Blood-Group System; D000483:Alleles; D001788:Blood Grouping and Crossmatching; D005700:Galactosyltransferases / Q000097:blood* / Q000378:metabolism*; D005838:Genotype; D006801:Humans; D007700:Kinetics; D007723:Korea / Q000453:epidemiology; D017720:Molecular Epidemiology; D017350:N-Acetylgalactosaminyltransferases / Q000097:blood* / Q000378:metabolism*; D016133:Polymerase Chain Reaction
D000017:ABO Blood-Group System; D005700:Galactosyltransferases; D017350:N-Acetylgalactosaminyltransferases; C003742:UDPgalactosamine-galactose acetylgalactosaminyltransferase; C099426:histo-blood group B transferase; C023155:blood-group-substance alpha-D-galactosyltransferase