Molecular characterization of human complement factor B subtypes.
While several laboratories have agreed that there are two subtypes of the BF*F alleles, no information has been available until now at the molecular level. The region of the BF gene corresponding to the Ba fragment [1.7 kilobases (kb)] of the BF*S, BF*FA, and BF*FB alleles has been sequenced after specific amplification using the polymerase chain reaction (PCR). A point mutation at codon 7 has been revealed converting a cytosine in the BF*S allele to a thymidine in BF*FB. At the translational level an arginine residue in BF*S is substituted for a tryptophan residue in BF*FB. The amino-terminal sequencing of factor B immunoprecipitated from serum has been carried out from microquantities of protein blotted onto polyvinylidene fluoride (PVDF) membranes. We have shown that the difference between the BF*FA and the BF*FB subtypes in characterized by a glutamine at position 7 in BF*FA and a tryptophan in BF*FB.
Davrinche
C
C
INSERM, Unité 100, CHU Purpan, Toulouse, France.
Abbal
M
M
Clerc
A
A
D001483:Base Sequence; D003001:Cloning, Molecular; D011415:Complement Factor B / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping
D011415:Complement Factor B