Fig. 4. Efficiency of Hox protein translation. (A) In vitro translation products of synthetic PG1 Hox gene mRNAs analyzed by SDS-PAGE electrophoresis. Protein products of the expected size are efficiently produced in vitro. Predicted sizes: long form of hoxa1a, 36 kDa; hoxb1a, 35 kDa; hoxb1b, 34 kDa; long form of hoxc1a, 34 kDa. Molecular weight marker sizes in kDa are indicated. (B) Western blot analysis of Myc-tagged Hox proteins synthesized in vivo after micro-injection of 50 ng/µl concentrations of each PG1 mRNA. Lysates of whole embryos were prepared at the 20-22 hour stage and 10 µg of total extracted protein electrophoresed and blotted. As expected, Myc-tagged proteins (six Myc-epitopes) are approximately 10 kDa larger that untagged versions. Molecular weight marker sizes in kDa are indicated.