Hello, my name is Linda Spremulli and I'm going to talk today about the process of
"Initiation and Elongation in Mammalian Mitochondrial Protein Synthesis.
I'm from the University of North Carolina at Chapel Hill and I've got the pleasure of
being a participant in one of these HSTalks on mammalian mitochondria.
We're going to talk briefly about an introduction,
then we'll concentrate on chain initiation in mitochondria,
we'll look at a model for chain elongation,
we'll talk briefly about the role of the membrane,
we'll talk about translational regulation,
what little is known about it,
and we'll have some brief conclusions.
On the next slide, we see one of the interesting features of
the mammalian mitochondrial translation system,
and that is it's unusual genetic code.
For example, in the universal code UGA is a stop codon.
In mammalian mitochondria, it specifies the amino acid tryptophan.
One of the most interesting alterations is the use of
AUA isoleucine codon in
the universal code which specifies methionine in the mitochondria of mammals.
This is a particularly interesting change because
methionine serves both for initiation and for chain elongation.
Methionine uses AUG for most of the translation start sites,
10 out of 13 in the bovine system but AUA is
the dominant methionine codon in the elongation cycle.
Another alteration is the use of AGA and AGG arginine universally,
they're is simply unassigned in the mammalian mitochondria.
The genetic code of mammalian mitochondria is translated with
the use of tRNAs that are somewhat unusual as indicated on the next slide.