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. 2016 Apr 6;310(11):C911–C920. doi: 10.1152/ajpcell.00029.2016

Fig. 2.

Fig. 2.

Sea urchin SpABCC1 gene has 4 forms of exon 22 that correspond to membrane-spanning domain 2 (MSD2) of SpABCC1 transporters. A: gene structure of sea urchin SpABCC1 shows that it consists of 33 exons, 4 of which encode exon 22. Arrows indicate positions of primers used to determine the quantitative PCR (qPCR) profiles of SpABCC1α (green) and SpABCC1δ (blue) splice variants and pan-SpABCC1 (black). B: qPCR expression profiles of SpABCC1α and SpABCC1δ show that both genes are expressed throughout embryonic development and that the SpABCC1α expression profile is similar to the pan-SpABCC1 expression profile. Values are means ± SD. C: variable exon 22 corresponds to a region in MSD2 marked in red. This exon encodes part of transmembrane segment 13 (TM13), cytoplasmic loop 6 (CL6), all of TM14, and part of TM15. Alignment of sea urchin SpABCC1 exon 22 splice variants with human multidrug resistance protein (MRP) 1 exon 24 indicates that some residues are conserved. D: protein sequence percent identity matrix of 4 splice variants of sea urchin exon 22 and the corresponding regions in human MRP1, MRP2, MRP3, and MRP6. Bold and underlined numbers indicate percent similarity of exon 22 of SpABCC1α in relation to the human MRP transporter sequences.