cellular processes without proteins

Bob Gross bob.gross at dartmouth.edu
Wed Feb 2 12:43:34 EST 1994

Tim -

I am not aware of any processes that occur without proteins in vivo,
but there really is no such thing as a naked RNA or DNA in the cell -
there are always proteins interacting with nucleic acids. Having said
that, there are a number of enzymes that have active RNA components:
RNAase P (tRNA processing in prokaryotes), telomerase ("replication" in
eukaryotes), signal recognition particle (SRP - binding of ribosomes to
endoplasmic reticulum), and of course all the RNA splicing enzymes
containing snRNAs. Some RNA precursors, such as pre-rRNA in
Tetrahymena, can remove their own introns without any proteins in
vitro, but these RNAs are likely to be associated with proteins in the
cell. There is also very good evidence that the peptidyl transferase
activity of ribosomes relies on the rRNA for catalytic activity,
although ruling out proteins is problematic. There are other examples
of catalytic RNAs, but this should get you started.

Bob Gross
Dept. of Biology, Dartmouth College
bob.gross at dartmouth.edu

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