Ja. Chaddock et al., A HYDROPHOBIC REGION OF RICIN-A-CHAIN WHICH MAY HAVE A ROLE IN MEMBRANE TRANSLOCATION CAN FUNCTION AS AN EFFICIENT NONCLEAVED SIGNAL PEPTIDE, Biochemical and biophysical research communications, 217(1), 1995, pp. 68-73
Ricin A chain is a polypeptide of 267 amino acids containing a hydroph
obic region near its carboxyl-terminus (residues 245-256) which has be
en implicated in the membrane translocation step necessary for this ca
talytically active toxin to reach its intracellular substrate. DNA fus
ions were constructed that encoded hybrid proteins consisting of carbo
xyl-terminal residues 233-267 or residues 238-267 of ricin A chain pre
ceding mouse dihydrofolate reductase. When in vitro transcripts prepar
ed from these constructs were translated in cell-free systems, the ric
in A chain-derived sequences functioned as efficient signal peptides w
hich directed dihydrofolate reductase into microsomes or into proteoli
posomes containing microsomal membrane components. (C) 1995 Academic P
ress, Inc.