Receptor binding profiles of NPY analogues and fragments in different tissues and cell lines

To investigate receptor selectivity and possible species selectivity of a number of NPY analogues and fragments, receptor binding studies were performed using cell lines and membranes of several species. NPY displays 4-25-fold higher affinity for the Y2 receptor than for the Y1 receptor. The affinity of [Leu31,Pro34]NPY is 7-60-fold higher for the Y1 receptor when compared with the Y2 subtype. Species selectivity within the Y2 receptors is demonstrated by PYY(3-36), NPY(2-36), NPY(22-36), and NPY(26-36). It is shown that NPY(22-36) is species selective for the human Y2 subtype (K1 of 0.3 nM) compared with the rabbit and rat Y2 receptor (K1 of 2 and 10 nM, respectively). PYY(3-36) displays highest affinity for the human and rabbit Y2 subtype (K1 of 0.03 and 0.17 nM). The screening of NPY analogues and fragments revealed that highest affinity for the human Y2 receptor is shown by NPY(2-36) and PYY(3-36). In addition, PYY(3-36) and NPY(2-36) are not only subtype selective, but also species selective.