(full paper is archived in the Miller Library)
Title: Ubiquitin-conjugate levels show variation and
occasional clearing in Anthopleura elegantissima in the
field
Student Author(s): Hong, Deborah W.
Faculty Advisor(s): Somero, George
Pages: 24
Location: Final papers biology 175H
Date: June 2005
Abstract: The ubiquitin-proteasome proteolytic pathway is a
specific and tightly regulated means by which intracellular proteins,
including proteins involved in cell cycle regulation, transcriptional
activators, and cell surface receptors, are degraded. Proteins may be
degraded because they are no longer needed or because they are
mutated, denatured, or misfolded. Each protein substrate is
covalently tagged by several 76-amino acid ubiquitin molecules; the
tagged protein is degraded by the 26S proteasome complex, releasing
free ubiquitin. Deubiquitinating enzymes regulate the generation and
recycling of ubiquitin levels in the cell. This field study examined
trends in ubiquitin-conjugate levels in Anthopleura
elegantissima in order to determine whether overall changes in
ubiquitin-conjugate levels are detectable and significant and also to
observe the timescale of any such cycles of conjugate build-up and
clearing. Levels of ubiquitin-conjugates in the field in A.
elegantissima were examined every four hours over a four day
period at two sites by Western blots and dot blots using an
anti-ubiquitin-conjugate antibody (Lars Tomanek, Somero Lab). Mean
pooled intensities of dot blot wells revealed occasional clearing of
ubiquitin conjugates over the collection period with no difference
between the two sites, suggesting that at some time points, all
detectable ubiquitin must be in its free form or itself been
degraded. Time series analysis revealed no significant predictive
factors that correlated to ubiquitin-conjugate levels. Factors
examined were exposure to sun, presence of rain, immersion/emersion
conditions prior to and at the time of sampling, extrapolated tidal
height, time of day, and anemone body temperature.