Wednesday, June 2, 2010

The Word: "Sphingolipid"

[This is a draft of something that may be published soon. I'm just giving it a trial run here.]

If good fences make good neighbors, then good membranes make good cells. Sphingolipids are some of the "bricks" in the membranes of blood and brain cells. The first researcher to define them revealed his frustration in the name he coined a century ago: the prefix “sphingo-” refers to the Sphinx, the original mythological riddler and bane of ancient travelers.


There are at least 60 different sphingolipids, many still as enigmatic as, well, the Sphinx. Some general riddles have been solved. Sphingolipids are chemically well-built and sturdier than most other lipids in the membrane. Also, they are extroverted molecules that sit on the outside of the cell, pointing at and talking to the rest of the body. Your immune system constantly surveys your blood cells’ sphingolipids and has grown accustomed to them (cue Sinatra and Bono’s duet, “I’ve Got You Under My Skin”).


In fact, the shape of the sugars on your sphingolipids determines your blood type, whether A, B, or O. The difference between A-type and B-type blood is just six tiny atoms (one “N-acetyl” group), but your immune system detects the difference, like the princess and the pea. If blood is transfused into your bloodstream with an unfamiliar sphingolipid, your immune system concludes that it’s under attack and defensively musters up a life-threatening overreaction. Sometimes the immune system’s reaction to innocuous substances can be too much of a good thing.

No comments: