English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Most species of invertebrate animals cannot synthesise sterols  de novo  and many that feed on plants dealkylate phytosterols (mostly C 29  and C 28 ) yielding cholesterol (C 27 ). The final step of this dealkylation pathway involves desmosterol reductase (DHCR24)-catalysed reduction of desmosterol to cholesterol. We now report the molecular characterisation in the silkworm,  Bombyx mori , of such a desmosterol reductase involved in production of cholesterol from phytosterol, rather than in  de novo  synthesis of cholesterol. Phylogenomic analysis of putative desmosterol reductases revealed the occurrence of various clades that allowed for the identification of a strong reductase candidate gene in  Bombyx mori  (BGIBMGA 005735). Following PCR-based cloning of the cDNA (1.6 kb) and its heterologous expression in  Saccharomyces cerevisae , the recombinant protein catalysed reduction of desmosterol to cholesterol in an NADH- and FAD- dependent reaction.  Conceptual translation of the cDNA, that encodes a 58.9 kDa protein, and database searching, revealed that the enzyme belongs to an FAD-dependent oxidoreductase family. Western blotting revealed reductase protein expression exclusively in the microsomal subcellular fraction and primarily in the gut. The protein is peripherally associated with microsomal membranes. 2D-native gel and PAGE analysis revealed that the reductase is part of a large complex with molecular weight approximately 250kDa. The protein occurs in midgut microsomes at a fairly constant level throughout development in the last two instars, but is drastically reduced during the wandering stage in preparation for metamorphosis. Putative Broad Complex transcription factor-binding sites detectable upstream of the DHCR24 gene may play a role in this down-regulation.

Characterisation of a Desmosterol Reductase Involved in Phytosterol Dealkylation in the Silkworm, Bombyx mori