Albumin banks peninsula: a new termination variant characterised by electrospray mass spectrometry.
Albumin Banks Peninsula is an electrophoretically fast variant that is expressed at only 2% of the total serum albumin. Electrospray ionisation analysis indicated a mass decrease of 755 Da relative to normal albumin and carboxypeptidase A digestion, together with CNBr peptide mapping, indicated a C-terminal truncation. This was confirmed by PCR and DNA sequence analysis which showed the introduction of a new AG acceptor splice site near the 3' end of intron 13. Predictably this results in the replacement of the C-terminal GKKLVAASQAALGL sequence by SLCSG and would be associated with an 861 Da decrease in molecular mass. We surmised that the new Cys was most probably cysteinylated as this albumin species would have a mass decrease of 742 Da and be very close to the measured value of 755 Da. Cysteinylation was confirmed when a mass decrease of 863 Da was measured between the proteins after reduction of their disulfide bonds.
Brennan
S O
SO
Molecular Pathology Laboratory, Canterbury Health Laboratories, Christchurch Hospital, Christchurch, New Zealand.
Fellowes
A P
AP
George
P M
PM
D000595:Amino Acid Sequence; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002850:Chromatography, Gel; D003545:Cysteine / Q000737:chemistry; D006801:Humans; D007438:Introns; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012709:Serum Albumin / Q000737:chemistry* / Q000235:genetics; D000075462:Serum Albumin, Human
D012709:Serum Albumin; C121412:albumin Banks Peninsula; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D003545:Cysteine; D000075462:Serum Albumin, Human