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. 2019 Dec 18;7:341. doi: 10.3389/fcell.2019.00341

FIGURE 2.

FIGURE 2

(A) Generation of PP1γ isoforms. The Ppp1cc contains 8 exons and 7 introns. The Pp1γ1 mature mRNA (2.3 kb) contains exons 1 through 7. Intron 7 is retained as an extended exon leading to the eight amino acid C-terminus of PP1γ1 (note that “exon 8” is part of its 3′UTR). The PP1γ1 encodes a protein containing 323 amino acids derived from the seven exons along with the 8 amino acid C-terminus from the extended exon 7. In the post-meiotic germ cells in testis the intron 7 is spliced out, thus, producing a shorter Pp1γ2 transcript of approximately 1.7 kb. Exon 8 codes for the 22 amino acid C-terminus in PP1γ2. Thus, the amino acid sequences of PP1γ1 and PP1γ2 are identical in all respects except for their extreme C-termini. (B) Constructs for generating transgenic PP1γ1 mice. Rescues I–III constructs contain the entire or a portion of intron 7 which is part of the 3′UTR of the messenger RNA for PP1γ1. There was little or no transgenic expression of PP1γ1 in testis of mice generated from these constructs. The last rescue construct (Rescue IV) lacks the 0.9 kb region of intron 7 following the stop codon in PP1γ1 mRNA. Transcript from this construct will resemble PP1γ2 mRNA except that PP1γ1 protein will be produced. The transgenic mice produced from this construct expressed high testis levels of transgenic PP1γ1 and rescued spermatogenesis but not sperm fertility.