Natural rubber (polyisoprene) from the rubber tree Hevea brasiliensis is synthesized by specialized cells called laticifers. It is not clear how rubber particles arise, although one hypothesis is that they derive from the endoplasmic reticulum (ER) membrane. Here we cloned the genes encoding four key proteins found in association with rubber particles and studied their intracellular localization by transient expression in Nicotiana benthamiana leaves. We show that, while the cis-prenyltransferase (CPT), responsible for the synthesis of long polyisoprene chains, is a soluble, cytosolic protein, other rubber particle proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and Hevea rubber transferase 1-REF bridging protein (HRBP) are associated with the endoplasmic reticulum (ER). We also show that SRPP can recruit CPT to the ER and that interaction of CPT with HRBP leads to both proteins relocating to the plasma membrane. We discuss these results in the context of the biogenesis of rubber particles.
The Joint Advisory Group on Gastrointestinal Endoscopy (JAG) was initially established in 1994 to standardise endoscopy training across specialties. Over the last two decades, the position of JAG has evolved to meet its current role of quality assuring all aspects of endoscopy in the UK to provide the highest quality, patient-centred care. Drivers such as changes to healthcare agenda, national audits, advances in research and technology and the advent of population-based cancer screening have underpinned this shift in priority. Over this period, JAG has spearheaded various quality assurance initiatives with support from national stakeholders. These have led to the achievement of notable milestones in endoscopy quality assurance, particularly in the three major areas of: (1) endoscopy training, (2) accreditation of endoscopy services (including the Global Rating Scale), and (3) accreditation of screening endoscopists. These developments have changed the landscape of UK practice, serving as a model to promote excellence in endoscopy. This review provides a summary of JAG initiatives and assesses the impact of JAG on training and endoscopy services within the UK and beyond.