Polynucleotide and polypeptide sequences are described. The polypeptide sequences comprise one or more of: (a) a polypeptide having the deduced amino acid sequence translated from the polynucleotide sequence in SEQ ID NO: 1 or SEQ ID NO: 5 and variants, fragments, homologues, analogues and derivatives thereof; (b) a polypeptide of SEQ ID NO: 2 and variants, fragments, homologues, analogues and derivatives thereof; (c) a polypeptide encoded by the cDNA of NCIMB 41110 and variants, fragments, homologues, analogues and derivatives thereof; or (d) a polypeptide which has at least 78% identity to (i) the polypeptide encoded by the polynucleotide of SEQ ID NO: 1 or SEQ ID NO: 5, (ii) the polypeptide of SEQ ID NO: 2, or (iii) the polypeptide encoded by the cDNA of NCIMB 41110. Such polypeptide sequences are, inter alia, useful in the prophylaxis and/or treatment of sexual dysfunction, in particular male erectile dysfunction (MED) or female sexual dysfunction (FSD), preferably female sexual arousal disorder (FSAD).