Ubiquitin Conjugation to Protein Increases following Chilling of Clerodendrum Leaves.

The protein content of clerodendrum (Clerodendrum speciosum) leaves declines following chilling (48 h, 3 degrees C). Using western and dot blots and fluorescence immunoassays, we found that isolated leaf proteins had more conjugated ubiquitin following chilling. In contrast, the amount of free ubiquitin declined by almost 90% after chilling. The increase in ubiquitin conjugation was greater in the membrane fraction than in the soluble fraction.