Lipocalins are remarkably diverse at the sequence level yet have highly conserved
structures. Most lipocalins share three characteristic conserved sequence motifs–the kernel
lipocalins–while others are more divergent family members–the outlier lipocalins–typically
sharing only one or two. This classification is a useful tool for analysing the family, and within
these large sets are smaller groups sharing much higher levels of sequence similarity. The
lipocalins are also part of a larger protein superfamily: the calycins, which includes the fatty …