Api g 4 (Celery Profilin)

Allergen Data Collection: Celery (Apium graveolens)
Internet Symposium on Food Allergens 2(3):145 -67 (2000) [http://www.food-allergens.de]

6.4 Properties of Celery Profilin

6.4.1 Molecular Biological Properties

Celery Profilin References

Allergen Nomenclature Api g 4 (1) Larsen & Lowenstein 2000

Isoallergens and Variants
Double band in SDS-PAGE (1, 2) (1) Vallier et al. 1992
(2) Jankiewicz et al. 1998

Molecular Mass
calculated: 14.3 kDa (3)
SDS-PAGE: 15 kDa (1), 15-16 kDa (2) (1) Vallier et al. 1992
(2) Jankiewicz et al. 1998
(3) Scheurer et al. 2000

Isoelectric Point
calculated: pI 4.54 (2)
2D-PAGE: pI 5.80 - 5.90 (1)
(1) Vallier et al. 1992
(2) Scheurer et al. 2000

Amino Acid Sequence,mRNA, and cDNA

Profilin

SWISS-PROT:

GenBank: AF129423

Amino Acids 133

mRNA 405 bp

cDNA (open reading frame) 399 bp

(1) Scheurer et al. 2000

recombinant Protein
Expression in Escherichia coli:
PCR amplification of cDNA and expression of rApi g 4 in E.coli BL21DE3 using a modified pET-30a vector (1) (1) Scheurer et al. 2000

Biological Function
Profilin family (1) (1) Vallier et al. 1992

Sequence Homology
aa sequence identities to birch pollen profilin (Bet v 2) 80%, soybean profilin (Gly m 3) 78%, wheat profilin 78%, maize profilin 77%, kidney bean 76%, and barley profilin 75% (1, 2)
aa sequence identity to human profilin: 33% (2) (1) BLAST at NBCI
(2) Scheurer et al. 2000

6.4.2 Allergenic Properties

Celery Profilin References

Frequency of Sensitization
IgE-binding to profilin in appr. 23-58% of patients (1) (1) see 6.1 Sensitization to Celery Allergens

IgE-Binding Mimotope
A synthetic peptide (CAISGGYPVC) defined by phage display (using random nonapeptide libraries screened with anti- profilin antibodies from an exclusively profilin allergic patient) inhibited IgE binding to celery tuber profilin (immunoblot). This peptide is considered to mimic a common conformational IgE epitope of profilins (1) (1) Leitner et al. 1998b

Allergenicity of recombinant Api g 4
(1) 22 celery allergic patients (DBPCFC positive): 5 sera bound to natural and rApi g 4 in SDS-PAGE immunoblot and to rApi g 4 in EAST; inhibition of IgE binding from 1 patient's serum to rApi g 4 by native celery extract and rApi g 4 and to native Api g 4 from celery extract by rApi g 4 (immunoblot)
(2) 23% of 13 celery allergic patients (DBPCFC positive) and 88% of 8 birch profilin (Bet v 2) reactive sera reacted to rApi g 4 (immunoblot); IgE binding to rApi g 4 completely inhibited by celery extract in 9 sera and nearly completely by rBet v 2 in 2 sera; partial inhibition by rBet v 2 in 7 sera (immunoblot inhibition); complete inhibition of IgE binding to natural Api g 4 by rApi g 4 (2 sera and pooled serum, immunoblot inhibition); EAST inhibition with 1 serum (rApi g 4 vs. rBet v 2); Similar potencies of rApi g 4 and rBet v 2 in histamine release from basophils from 1 patient (1) Lüttkopf et al. 2000
(2) Scheurer et al. 2000

Celery Profilin	References
*Frequency of Sensitization* IgE-binding to profilin in appr. 23-58% of patients (1)	(1) see 6.1 Sensitization to Celery Allergens
*IgE-Binding Mimotope* A synthetic peptide (CAISGGYPVC) defined by phage display (using random nonapeptide libraries screened with anti- profilin antibodies from an exclusively profilin allergic patient) inhibited IgE binding to celery tuber profilin (immunoblot). This peptide is considered to mimic a common conformational IgE epitope of profilins (1)	(1) Leitner et al. 1998b
*Allergenicity of recombinant Api g 4* (1) 22 celery allergic patients (DBPCFC positive): 5 sera bound to natural and rApi g 4 in SDS-PAGE immunoblot and to rApi g 4 in EAST; inhibition of IgE binding from 1 patient's serum to rApi g 4 by native celery extract and rApi g 4 and to native Api g 4 from celery extract by rApi g 4 (immunoblot) (2) 23% of 13 celery allergic patients (DBPCFC positive) and 88% of 8 birch profilin (Bet v 2) reactive sera reacted to rApi g 4 (immunoblot); IgE binding to rApi g 4 completely inhibited by celery extract in 9 sera and nearly completely by rBet v 2 in 2 sera; partial inhibition by rBet v 2 in 7 sera (immunoblot inhibition); complete inhibition of IgE binding to natural Api g 4 by rApi g 4 (2 sera and pooled serum, immunoblot inhibition); EAST inhibition with 1 serum (rApi g 4 vs. rBet v 2); Similar potencies of rApi g 4 and rBet v 2 in histamine release from basophils from 1 patient	(1) Lüttkopf et al. 2000 (2) Scheurer et al. 2000