ISOLATION OF INTRAMITOCHONDRIAL HELICAL FILAMENTS APPEARING IN OUTER COMPARTMENT OF MITOCHONDRIA

Background: Packets of helical filaments have been observed in the outer compartment of occasional mitochondria in many cell types in a variety of animals. The compositon and funcation of these intramitochondrial helical filaments (IMHF) are unknown. Methods: IMHF wre induced in a hepatic mitochondria by administration of ethanol in the drinking water of rats. Hepatic mitochondria were isolated and ruptured by osmotic shock, relasing their IMHF. To purify these structures, the IMHF-containing supernatant was further fractionated by ammonium sulfate precipitation, a 50–60% solution of this reagent being the most effective in this regard. Isolated IMHF were examined by electron microcopy and were analyzed by SDS-PAGE. Result Isolated IMHF closely resembled their in situ counterparts: they had a right-handed helical structure with a 16 nm pitch. SDS-PAGE analysis revealed that they contained three polypeptides with weigh tmolecular of 135, 98, and 53 kD, respectively. Conculusions: These observations will stand as a aseline for comparisons with IMHF that occur naturally or that are induced in other cell types by other kinds of experimental manipulation. © 1995 Wiley-Liss, Inc.