The molecular chaperone mhsp72 is partially associated with the inner mitochondrial membrane both in normal and heat stressed Spinacia oleracea.

The mitochondrial molecular chaperones mhsp70 and hsp60 in yeast have been shown to be essential components of the protein import and assembly machinery. Using the Western blotting technique and heterologous antibodies we have found that in spinach leaf mitochondria, a 72 kDa protein was an analogue of the mhsp70 and a 58 kDa protein, an analogue of the hsp60. Surprisingly, 49% of the spinach mhsp72 was associated with the membrane. The spinach hsp58 was entirely located in the matrix. The mhsp72 was loosely bound to the mitochondrial inner membrane. The heat shock treatment of the intact spinach plants resulted in a 2.4-fold induction of the mhsp72 and additionally facilitated association of this chaperone with the mitochondrial membrane.