Zebrafish 154 leptin-b proteins are predicted to have a third
cyst 155 eine residue that may or may not be available for intra- or
intermolecular 156 disulphide bridging [a feature also present in
fish
inter 157 leukin-11(a and b) proteins (Huising et al., 2005)]. This
cyst 158 eine may facilitate some differentiation between the functions
of 159 zebrafish leptins. However, this extra cysteine is not a universal
feature 160 among teleosts, as other
fish leptin-b sequences, including
salmon 161 (Rønnestad et al., 2010) and medaka (Kurokawa and
Murashita, 162 2009), lack this cysteine, suggesting that if this amino
acid 163 is important in zebrafish leptin signalling, it may be species-
specific. 164 From our tertiary structure models we cannot conclude
whether 165 the third cysteine residue is at the very border of the
pro 166 tein surface and thus available for disulphide bridging or
embedded 167 in the protein interior