Worm Breeder's Gazette 11(2): 72
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The trans-spliced RNA leader might play a role in regulating the translation and/or stability of SL-containing mRNAs. This possibility led us to seek transacting factors that might mediate this regulatory function. Protein factors from C. elegans cells (either embryos or worms from mixed stages) that bind with high specificity to the trans- spliced RNA leader sequence (SL) have been identified. Whole cell extracts were shown by a mobility shift electrophoresis assay to form two RNA-protein complexes involving the SL1 sequence. Complex formation could be abolished by preincubation with excess, unlabeled competitor SL1-containing RNA (which is the 5' non-coding region of actin-1 mRNA fused to the firefly luciferase coding region) but not by nonspecific, control RNA that did not contain an SL1 sequence. Spliced leader binding protein-1 (SLBP1) is distinct from SLBP2. The binding of these proteins to SL1 is cap dependent though independent of the detailed structure of the cap; either monomethyl- or trimethyl guanosine cap stimulates binding. We are purifying SLBP1 and SLBP2. Future work will be focused on the characterization of these proteins and elucidation of their biological functions.