Characterization of the primary gene product of rat incisor .alpha.-phosphophoryn

Publisher Website
Google Scholar
Abstract
The nature of the primary gene product for the .alpha.-phosphophoryn component of rat incisor dentin has been examined by cell-free translation of the total RNA and poly(A+) mRNA from rat maxillary incisors, including pulp cells and odontoblasts. The RNA was extracted by the guanidinium thiocyanate method and translated in a rabbit reticulocyte system. The translated proteins were analyzed by gradient gel electrophoresis, and .alpha.-phosphophoryn was identified by isolation on an anti-rat .alpha.-phosphophoryn antibody coupled Sepharose column and dot-blot procedures. The major protein identified as .alpha.-phosphophoryn had a molecular weight of 153000 (.+-. 5000) and had chromatographic properties similar to those of .alpha.-phosphophoryn. Since tissue-isolated rat phosphophoryn has a molecular weight of only .apprx. 90,000 when fully phosphorylated, it appears that the primary gene product is a prepro-.alpha.-phosphophoryn. Thus, .alpha.-phosphophoryn in the extracellular space of rat incisor dentin must be the product of one or more posttranslational proteolytic processing steps.