| Citation | Graham Warren has made major contributions to the understanding of membrane organisation in higher cells, particularly of the Golgi apparatus. By combining biochemistry and electron microscopy he showed that proteins destined for the plasma membrane pass through each cisterna of this organelle, and demonstrated that it contains at least three distinct functional compartments which can be distinguished by their content of oligosaccharide modifying enzymes. He discovered that one of these enzymes, beta-1,4-galactosyltransferase, is retained in the correct part of the Golgi apparatus by its membrane-spanning domain and flanking regions, and has proposed a model to account for the way in which this is achieved. Warren has elucidated in detail the fate of the Golgi complex during mitosis. He found that transport to the plasma membrane is inhibited, while Golgi cisternae fragment and partition between daughter cells. He proposed that this fragmentation is a consequence of the continued budding of transport vesicles without their subsequent fusion, and has provided biochemical and morphological evidence that strongly supports this model. He has also been at the forefront of efforts to develop cell-free assays to study these and related processes, most notably devising assays that reconstitute all of the early steps on the pathway of receptor-mediated endocytosis. |