RIBOSOMAL P ANTIGEN 
AROTEC_RiboP_Product_Info.pdf Version/Date: B/04.05.25 
ATR03-02 Ribosomal P antigen 0.20 mg 
ATR03-05 Ribosomal P antigen 0.50 mg 
ATR03-10 1.0 mg 
_________________________________________________________________________________
Description of the Product
Purified from bovine thymus. After coating onto ELISA plates 
the product will bind autoantibodies to ribosomal P antigen. 
Purity: The ribosomal P antigen subunits P0, P1 and P2 （38, 
19 and 17 kDa respectively） are more than 90% pure, as 
assessed by SDS-polyacrylamide gel electrophoresis. 
Concentration: 0.1-1.0 mg protein/ml. 
Storage: The product is stabilised with 20% glycerol and 0.1% 
Micr-O-protectTM. Store at -20 o
C or below （long term） or at 
+4o
C （short term）. Avoid repeated freezing and thawing. Mix 
thoroughly before use. 
Clinical and Biochemical Data 
The existence of autoantibodies to ribosomal components has 
been known for some time1,2. In 1985, two groups 
independently identified the ribosomal P proteins as the major 
protein antigens recognised by ribosomal antibodies3,4. Antiribosomal P antibodies are considered to be very specific for 
systemic lupus erythematosus （SLE）5,6, and their presence 
frequently correlates with disease activity, in particular 
psychotic depression6
, hepatitis7-9, and nephritis10,11. Although 
anti-ribosomal P antibodies have been reported to occur in 
patients with systemic sclerosis12, this would appear to be rare 
and normally indicates an overlap with SLE13
.
The P proteins are three of approximay 80 proteins that 
make up the largest cytoplasmic ribonucleoprotein, the 
ribosome. Since ribosomes are assembled in the nucleoli, 
high titre anti-ribosomal P sera will show nucleolar as well as 
cytoplasmic immunofluorescent staining14. The exact functions 
of the individual P proteins are not fully understood however 
studies suggest that they collectively comprise part of a 
functional GTPase domain necessary for the binding of factorGTP complexes15,16. This interaction results in catalysis of the 
appropriate step of the protein synthesis cycle （initiation, 
elongation or release）. GTP is hydrolysed and the factor is 
released. The ribosomal P proteins are distinctive through 
their overall net negative charge, high content of alanine and 
predicted secondary structure （approx. 70% helical）14. The Cterminal 17 amino acids of all three P proteins are virtually 
identical and are highly conserved between species. Although 
the major autoantibody epitope on all three proteins is 
believed to be located within the C-terminal 22 amino 
acids14,17, there is recent evidence that other individual P 
protein-specific epitopes occur18
. 
The ribosomal P0, P1 and P2 proteins are all present in 
AroTec’s ribosomal P antigen. The antigen typically exhibits a 
260/280 nm absorbance ratio of >1.5, suggesting that a 
significant rRNA component is present. The sequences of the 
bovine P0 and P2 proteins have been determined19, and 
found to be very homologous （>99%） to their human 
equivalents20. In particular the C-terminal 22 amino acids of 
both species were found to be identical. 
Methodology
The following is an ELISA procedure which can be used to 
detect anti-ribosomal P autoantibodies in human serum using 
the ATR03 purified autoantigen: 
1. Dilute the purified antigen to 0.5-1.0 µg/ml in PBS （10 mM 
potassium phosphate, pH 7.4, 0.15 M NaCl）. 
2. Coat ELISA plates with 100 µl of diluted antigen per well. 
Cover and incubate 24 hours at +4o
C. 
3. Empty the plates and remove excess liquid by tapping on a 
paper towel. 
4. Block excess protein binding sites by adding 200 µl PBS 
containing 1% BSA per well. Cover and incubate at +4o
C 
overnight. 
5. Empty plates and apply 100 µl of serum samples diluted 
1:100 in PBS / 1% BSA / 1% casein / 0.1% Tween?
 20. 
Incubate at room temperature for 1 hour. 
6. Empty plates and add 200 µl PBS / 0.1% Tween?
 20 per 
well. Incubate 5 minutes then empty plates. Repeat this step 
twice. 
7. Apply 100 µl anti-human IgG-enzyme conjugate 
（horseradish peroxidase or alkaline phosphatase） diluted in 
PBS / 1% BSA / 1% casein / 0.1% Tween?
 20 per well and 
incubate for 1 hour. 
8. Repeat step 6. 
9. Add enzyme substrate and stop the reaction when 
appropriate. 
10. Read absorbance in an ELISA spectrophotometer. 
References 
1. Sturgill, P.H. et al. （1965） Arthritis Rheum. 8, 213 
2. Schur, P.H. et al. （1967） Immunochemistry 4, 447 
3. Elkon, K.B. et al. （1985） J. Exp. Med. 162, 459 
4. Francoeur, A.-M. et al. （1985） J. Immunol. 135, 2378 
5. Elkon, K.B. et al. （1992） Rheum. Dis. Clin. 18, 377 
6. Teh, L.S. & Isenberg, D.A. （1994） Arthritis Rheum. 37, 307 
7. Koren, E. et al. （1993） Arthritis Rheum. 36, 1325 
8. Hulsey, M. et al. （1995） Clin. Immunol. Immunopathol. 74, 252 
9. Arnett, F.C. & Reichlin, M. （1995）, Am. J. Med. 99, 465 
10. Martin, A.L. & Reichlin, M. （1996） Lupus 5, 22 
11. Sato, T. et al. （1991） J. Rheumatol. 18, 1681 
12. Fujimoto, M et al. （1996） J. Dermatol. 23, 33 
13. Fujimoto, M. et al. （1995） Br. J. Rheumatol. 34, 908
14. Elkon, K.B. （1994） Man. Biol. Markers Dis. （Kluwer Acad. Publ.） 
 B2.5/1-11 
15. Chu, J.L. et a l. （1991） J. Exp. Med. 174, 507 
16. Teh, L.S. et al. （1992） Br. J. Rheumatol. 32, 287 
17. Elkon, K. et al. （1986） Proc. Natl. Acad. Sci. USA 83, 7419 
18. Fabien, N. et al. （1999） J. Autoimmun. 13, 103 
19. SWISS-PROT RLA0_BOVIN primary accession number Q95140 & 
 RLA2_BOVIN primary accession number P42899 
20. Rich, B.E. & Steitz, J.A. （1987） Mol. Cell Biol. 7, 4065 
Micr-O-protect is from Roche Diagnostics GmbH （Mannheim, 
Germany）. 
Tween?
 20 is a registered trademark of ICI Americas Inc. 
NOTE: No patented technology has been used by AroTec 
during the preparation of this product.