Photoactive probes have been introduced recently to study the hydrophobic sector of integral membrane proteins. A simple procedure to synthesize a new series of highly radioactive aryl azido-phospholipids is presented. They effectively exchange with the boundary lipids and, on illumination, the cross-link to several membrane proteins with high efficiency. The procedure and analysis of labelling of ATPase from sarcoplasmic reticulum is reported as an example. The advantages in using these photoactive phospholipids are discussed together with some information obtained on their use.
