Analysis of the cloned zebrafish β2 subunit gene and novel splice variants. Presentation and labeling as in Figure 1. A) Alignment of cloned human, rat, and zebrafish β2 amino acid sequences. Shown for zebrafish is the most conserved β2 splice form (variant B). S- = conserved cysteine in β2 that is a putative site of covalent linkage with a partner α subunit; S1 = nonsynonymous Hsβ2 single nucleotide polymorphism (SNP, C/T > R28W) (NCBI dbSNP, PharmGKB); S2 = nonsynonymous Hsβ2 SNP (G/A > R47H) (NCBI dbSNP, PharmGKB); GSCS = γ-secretase cleavage site. B) 5' and 3' RLM-RACE PCR and RT-PCR identified four distinct splice variants expressed from the zβ2 locus on zebrafish chromosome 15 (Ensembl). C) Splice donor and acceptor sites of zebrafish β2 splice variants. Zβ2 variants C and D both differ from the consensus sequences at the exon 4-intron 4 and intron 4-exon 5 splice junctions. D) Schematic diagram of β2 splice variants A-D. With the exception of variant A, the predicted proteins of zβ2 variants B-D differ only in the length of their intracytoplasmic C-terminal tail. Alignment of C-terminal tail of variants zβ2B, zβ2C, and zβ2D (below).