The venom-gland transcriptome of Hypsiglena sp. showed high expression and diversity of snake venom metalloproteinases. (A) Toxins were overrepresented in the high-abundance transcripts; the 23 most-abundant transcripts encoded toxins. (B) Total toxin-gene expression was high and commensurate with values from previously characterized viperids. (C) Toxin transcription consisted primarily of a diverse set of snake venom metalloproteinases and the unique Kunitz-Waprin domain fusion protein (i.e., fused toxin). Toxins detected proteomically are indicated with asterisks. Abbreviations: 3FTx–three-finger toxin, CTL–C-type lectin, CRISP–cysteine-rich secretory protein, KUN-Kunitz-type protease inhibitor, PDE–phosphodiesterase, NP–natriuretic peptide, SVMP–snake venom metalloproteinase, VEGF–vascular endothelial growth factor.