A new oligomeric parvalbumin allergen of Atlantic cod (Gad mI) encoded by a gene distinct from that of Gad cI.
BACKGROUND
The major allergen of Baltic cod (Gadus callarias) is a 12.3-kDa parvalbumin with two calcium-binding sites corresponding to EF-hand motifs. Our group found a 24-kDa IgE-reactive band that was also recognized by a monoclonal antiparvalbumin antibody in Atlantic cod (Gadus morhua). Our purpose was to purify and to determine the cDNA deduced sequence of this new cod allergen.


METHODS
Proteins from pre rigor mortis Atlantic cod were separated by gel filtration and the eluted peaks were analysed by SDS-PAGE and Western blotting with sera of sensitized patients and with antiparvalbumin. Protein bands were microsequenced, RNA transcripts were amplified by reverse transcription and polymerase chain reaction (RT-PCR) using primer combinations overlapping the open reading frame.


RESULTS
Four IgE and antiparvalbumin reactive proteins(12.5, 24, 38 and 51 kDa) were detected in gel filtration eluate. The cDNA deduced sequence of the 24 kDa protein had 109 amino acid residues with a molecular weight of 11.5 kDa and a theoretical pI of 4.34. The 24 kDa band corresponded therefore to a dimer of a beta-parvalbumin. Its homology was higher with Sal sI than with Gad cI. This new allergen was named Gad mI.


CONCLUSIONS
We have characterized a new parvalbumin allergen in Gadus morhua. This protein formed oligomers in native and in reducing conditions. Gad mI and Gad cI may correspond to two distinct genes of Gadus species.
Das Dores
S
S
Laboratoire de Pathologie Cellulaire et Moléculaire en Nutrition, EMI-INSERM 0014, URM IFREMER no. 20, Faculté de Médecine de Nancy, Université Henri Poincare, Vandouevre-lès-Nancy, France.
Chopin
C
C
Villaume
C
C
Fleurence
J
J
Guéant
J-L
JL
D000485:Allergens / Q000235:genetics* / Q000276:immunology; D000818:Animals; D015153:Blotting, Western; D018076:DNA, Complementary / Q000235:genetics*; D029941:Fish Proteins / Q000235:genetics* / Q000276:immunology; D005399:Fishes / Q000276:immunology*; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology; D006801:Humans; D010320:Parvalbumins / Q000235:genetics* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein
C033061:Allergen M protein, codfish; D000485:Allergens; D018076:DNA, Complementary; D029941:Fish Proteins; D010320:Parvalbumins