Fig. 1.

DIGE reveals ~ 900 spots per gel within the pH 4–7 range for synovial fluid. Spot filtering on ‘master gels’ reveals 143 protein spots which predominate in synovial fluid or plasma. Attention was focussed on a series of 26 synovial fluid proteins (circled in red) and 26 plasma proteins (circled in blue) as these spots remained unmatched or were expressed at a two-fold or higher level than could be detected in the corresponding fluid. Interestingly, the synovial fluid ‘specific’ proteins were all under ~ 60 KDa, whereas the plasma ‘specific’ had a wider molecular weight range from ~ 10 to 200 KDa. All 30 proteins spots were cut from replicate preparative gels and MALDI-TOF and nESI-MS/MS was used to ascertain their identity. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)