Prtg is preferentially expressed in the early stage of organogenesis. A semi-quantitative RT-PCR analysis of Prtg is compared at various embryonic stages and in various organs of postnatal mice. (A) As development proceeded from E10.5 to E14.0, the Prtg transcripts were dramatically decreased in the whole body. (B) In the postnatal mice, Prtg transcripts were detected only in the brain of the 10-week-old mice. However, they were remarkably reduced in comparison with that in the E10.5 whole body. Each organ group is represented by two samples. (C) According to an immunoblotting analysis, Prtg is expressed at substantially higher levels in the E10.5 mandible than in the E12.0 mandible. Prtg was dramatically decreased in the tooth germ at E18.0. The amount of the loaded protein is 10 μg in each lane.