Anti-Ribosomal P Protein Antibody (ARPA)

In light of the problems associated with diagnosing lupus cerebritis, a 1986 report of an association between antibodies to ribosomal P proteins and lupus cerebritis was very encouraging . This finding was based upon previous observations that patients with SLE were known to make antibodies which bound to ribosomes. Two groups reported that the targets of these antibodies were three phosphoproteins (P proteins) located on the 60S subunit of ribosomes . The proteins were designated P0, P1, and P2, with molecular weights of 35 kD, 19 kD, and 17 kD, respectively. They were thought to be involved in protein synthesis; specifically, in the interaction of EF-1 alpha and EF-2 with ribosomes. Evidence in support of this hypothesis is provided by observations that monoclonal antibodies to P proteins inhibit binding of these elongation factors to ribosomes , and also inhibit protein synthesis.