Michel, Rainer; Hallermayer, Gerhard; Harmey, Matthew A.; Miller, Fritz; Neupert, Walter
The 73 S ribosome of Neurospora crassa is the native mitochondrial ribosome.
In: Biochimica et Biophysica Acta - Nucleic Acids and Protein Synthesis, Vol. 478, Nr. 3: S. 316-330
The effect of the inclusion of EDTA and of heparin, in media used in the isolation of mitochondria, on the mitochindrial previous termribosomenext term has been investigated.
1. 1. Mitochondria isolated from previous termNeurospora crassanext term in the presence of EDTA contain only a single type of monomeric previous termribosome, viz. 73next term S.
2. 2. Mitochondria isolated in the presence of Mg2+ contain both 79-S and previous term73next term-S monomeric previous termribosomes.next term The heterogeneity of the previous termribosomesnext term was demonstrated by (a) ultracentrifugation on sucrose gradients, (b) electron microscopy, (c) immunoprecipitation with antibodies against mitochondrial previous term73next term-S and 79-S cytoplasmic previous termribosomes,next term (d) gel electrophoresis of high and low molecular weight RNAs.
3. 3. Inclusion of heparin in all media used for the isolation of mitochondria and previous termribosomesnext term resulted in (a) dissociation of previous term73next term-S mitochondrial previous termribosomesnext term into 50-S and 37-S subunits; (b) stabilization of 79-S cytoplasmic previous termribosomes;next term (c) in the case of mitochondria isolated in the presence of Mg2+ containing both previous term73next term-S and 79-S previous termribosomes,next term heparin causes the selective dissociation of the previous term73next term S monosome to yield previous termribosomesnext term containing only a single monomeric previous termribosomenext term type, viz. 79 S.
4. 4. It is concluded that (a) the 79-S previous termribosomesnext term present in mitochondria isolated in the presence of Mg2+ are contaminating cytoplasmic previous termribosomes,next term (b) the previous term73next term-S previous termribosomesnext term are the real functional mitochondrial previous termribosomes of Neurospora crassanext term.