Friday, November 07, 2008


A recent issue of Science included a foldout poster titled A Sequence-specificity Atlas of the Kinase World, compiled and published by Cell Signaling Technology, of which I reproduce here the central diagram. Part of the description:
Protein kinases are enzymes that mediate cellular decision processes by catalyzing the addition of a negatively charged phosphate group to protein substrates, which can subsequently be recognized by phosphorylation-dependent binding domains in other proteins. The human genome encodes 518 protein kinases, which have been organized into a tree that represents evolutionary relationships. The substrate specificities of kinases are in part determined by the amino acid sequence of the phosphorylation sites, and comprehensively mapping the consensus sequence motif recognized by each kinase catalytic domain is thus crucial for understanding phosphorylation mediated signaling networks.
I wish I knew enough biology to fully understand what's going on here, but one cannot look at the poster without grasping something of our evolutionary history, and indeed the marvelous complexity of what is going on in every cell of our bodies. The unraveling of the story of DNA to RNA to proteins to cellular chemistry is certainly the epic scientific story of my lifetime -- and there is more, much more, to come.

This morning on the way to college I picked up a bird nest that had fallen onto the ground, a small nest, beautifully constructed. Whatever bird made the nest was born knowing how to do it. It was there in the bird's DNA, that four-letter chemical code that not only directed the building of the bird's body, but also determined its songs, behaviors, and -- yes -- architecture. This is a story of such staggering wonderfulness that it is hard to get one's mind around it. There is no ghost in the machine, but the machine itself is vastly more spectacular than any ghost.

And those 518 kinases that catalyze my own machine? They are twigs on a beautiful evolutionary tree, strings of animo acids whose sequences reach far back in time, ultimately connecting me the the vast web of life on Earth. There's a grandeur in this view of life, said Darwin -- and he didn't know the half of it.