Figure 8
From: Phosphotyrosine recognition domains: the typical, the atypical and the versatile
Evolution of the human PTK signalling circuit. A schematic depicting the evolution of the human PTK circuit, where a, b, c, d, and e denote intracellular human circuits of a primitive origin, a, f, c, d, and e denote circuits with receptor tyrosine kinases and cytoplasmic substrates of bilaterian origin, and g, b, h, i and e denote vertebrate-origin circuits in which membrane-bound substrates are phosphorylated by cytoplasmic tyrosine kinases of a primitive origin in a tissue-specific manner. See reference [8] for more details.