Anti-Ro autoantibodies found in sera from patients with systemic lupus erythematosus and related diseases precipitate four RNAs (hY1-hY5) from human cell extracts. We identified two patient sera that selectively immunoprecipitated from such extracts the Ro particle containing the hY5 RNA (RohY5 particle). Using cell fractions either enriched in or depleted of RohY5 particles, we have shown that...

COP1 (CONSTITUTIVE PHOTOMORPHOGENIC 1), a ubiquitin E3 ligase, is a central negative regulator of photomorphogenesis. However, how COP1 activity is regulated by post-translational modifications remains largely unknown. Here we show that SUMO (small ubiquitin-like modifier) modification enhances COP1 activity. Loss-of-function siz1 mutant seedlings exhibit a weak constitutive photomorphogenic ph...

It has been reported that Arabidopsis phytochrome (phy) A and phyB are crucial photoreceptors that display synergistic and antagonistic action during seedling de-etiolation in multiple light signaling pathways. However, the functional relationship between phyA and phyB is not fully understood under different kinds of light and in response to different intensities of such light. In this work, we...

Arabidopsis (Arabidopsis thaliana) seedlings undergo photomorphogenesis in the light and etiolation in the dark. Light-activated photoreceptors transduce the light signals through a series of photomorphogenesis promoting or repressing factors to modulate many developmental processes in plants, such as photomorphogenesis and shade avoidance. CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is a conserved R...

The Z-box is one of the light-responsive elements (LREs) found in the promoters of light inducible genes. We have studied the light responsive characteristics of Z-box containing synthetic as well as native promoters. We show that promoters with Z-box as a single LRE or paired with another LRE can respond to a broad spectrum of light. The response is primarily mediated by phyA, phyB and CRY1 ph...

Previous studies have shown that COP1 (constitutive photomorphogenic 1) protein of Arabidopsis thaliana plays a crucial role in different aspects of photomorphogenesis. Interaction of COP1 with SPA1 (suppressor of phytochrome A) and other regulatory proteins actively affect light regulatory gene expression in diverse directions. Though several studies have explained the function of COP1 protein...

We investigated the mechanism by which the large T antigen (T-Ag) of both polyomavirus and simian virus 40 (SV40) promotes homologous recombination in mammalian cells. To this end, we constructed a rat cell line, designated Hy5, that carries two mutated copies of the polyomavirus middle-T-Ag (pmt) oncogene lying as direct repeats on the same chromosome. The structure of the viral insert was dev...