Generation of Ovca1-2- and Ovca1-specific knockout mice. (A) Gene targeting strategy to generate Ovca1 mutant alleles. The Ovca1-Ovca2 locus is shown at the top. (Boxes) Exons; (light shaded boxes) Ovca1 coding region; (dark shaded boxes) Ovca2 coding region; (open boxes) untranslated sequences. (P1 to P5) Primers used for RT-PCR analysis and genotyping. The targeting vectors and resulting Ovca1-specific and Ovca1-2 mutant alleles with the neo expression cassette removed are shown below. (neo-flox) loxP-flanked neomycin resistant cassette; (tk) HSV thymidine kinase expression cassette; (3X stop) XbaI linker containing multiple stop codons; (H) HindIII; (N) NotI; (S) StuI; (X) XbaI; (Xh) XhoI. (B) RT-PCR analysis of Ovca1 expression in Ovca1-2+/+, Ovca1-2+/-, and Ovca1-2-/- MEFs. The P3 and P4 primers were used to amplify Ovca1 transcripts spanning exons 1 to 13. P4 and P5 were used to amplify Ovca1 transcripts spanning exons 1 to 6. (RT +) With reverse transcriptase; (RT -) without reverse transcriptase. (C) RT-PCR analysis of Ovca1 and Ovca2 expression in Ovca1+/+, Ovca1+/-, and Ovca1-/- MEFs. The P3 and P4 primers were used to detect Ovca1 expression. The primers P2 and P3 were used to amplify Ovca2 transcripts. (D) Western blot showing OVCA1 protein in multiple organs (brain, lung, liver, and kidney) of E18.5 Ovca1+/+ but not Ovca1-/- mice. Arrow, 50-kD OVCA1 protein.