A rabbit anti-native rat phosphophoryn antibodies recognized human dentin phosphophoryn

Human dentin phosphophoryn, the major noncollagenous protein in dentin was recently cloned by our laboratory (Gu et al., 1998). DPP is believed to be a nucleator and a controller of dentin mineralization. The native DPP isolated from human immature tooth has a size of 140 kDa by Stains-All stainning. Objectives: It is essential to have an antibodies recognizing DPP for protein quantitation and developmental studies as well as immunolocalization of DPP in human teeth. Methods: A rabbit anti-rat dentin phosphophoryn antibodies was raised against native rat DPP. Results: This antibodies was tested against whole rat dentin extract and against purified rat PP and was found to be specific for PP, not reacting with DSP, by Western blot analysis. When this anti-rat PP antibodies was used for Western blot on human native DPP and total human dentin extract, a 140 kDa DPP band was recognized in both the purified human DPP and human dentin extract. In addition, we found that a high molecular weight protein (~210 kDa), in human DSP preparation and in human dentin extract, reacted strongly with the rabbit anti-rat DPP antibodies. This suggests that this 210 kDa band might be the DSP-PP precursor protein or another DPP related protein. Conclusions: We conclude that the rabbit anti-rat DPP antibodies has cross-species reaction with human DPP. This is the first report regarding cross-species recognition of an antibodies against a major dentin protein. Furthermore, using this antibodies we have detected a potential DSP-PP precursor protein or a DPP related protein in the human dentin matrix. This work is supported by NIH grant DE 11442 (HR) and DE12899(BHC).