Protein kinase D (PKD) is a serine/threonine kinase regulated by diacylglycerol signaling pathways with unique domain composition and enzymatic properties, still awaiting identification of its specific substrate(s). Kinase D-interacting substrate 220(Kidins220) is an enzyme that in humans is encoded by the KIDINS220 gene. It is an integral membrane protein selectively expressed in brain and neuroendocrine cells, where it concentrates at the tip of neurites. and it contains 11 ankyrin repeats and four transmembrane domains within the N-terminal region.