A novel 40-kDa protein induced by heat shock and other stresses in mammalian and avian cells.

When HeLa cells were exposed to heat shock or other stresses, a 40-kDa protein (p40) was induced in addition to the classical heat shock proteins with molecular sizes of 110-, 90-, 70-, and 47-kDa. The p40 was induced not only by heat shock but by arsenite and 2-azetidine carboxylic acid. Also, it was induced in rat, mouse and chick cells by these stresses. The p40 was a basic protein (pI divided by 9.2) as judged by two-dimensional gel electrophoresis. To our knowledge, p40 is a novel heat shock protein in mammalian and avian cells.