Pro-IL-1b is ~31 kDa. Therefore, on a high concentration SDS-PAGE, the band could move closer to 50 kDa marker. Therefore, a good separation on 9 or 10% PAGE may give you correct size.

Thanks. It was informative.  How does pro and mature IL1 beta differe drom each other. 

Pro-IL-1b (p31) is cleaved by activated caspase-1 (part of an inflammasome, a cytosolic protein complex) to cleaved secretory mature form (~17 kDa). 

Thank you for sharing your knowledge. 

Hi Naila,

During my scientific collaboration with many cancer and inflammation researchers then back in Russian Academy of Science in the 1980’s, and thereafter in National Cancer Institute, NIH, in the 1990s, there were numerous anecdotal stories about formation of IL1 beta trimers  (with m.m.  about  51.0 kD),  an aggregation of three proteolytically processed IL1 beta 17.5 kDa each. The appearance of those “trimers” was dependent on the composition of SDS-PAAG gel, quality of protease, and the origin of anti-IL1 beta antibody used.

The above might sound like a X-mass story, but it isn’t.

Best wishes,

Ilya

Hi Ilya,

Thank you for sharing your insight and intellectual knowledge. It was helpful.