peptides mr 165 mr 311 and mr 336 were fused to keyhole limpet haemocyanin klh before immunisation of rabbits for production of polyclonal antibodies the antibody mgo 5 was derived from rabbits immunised with the peptide mr 165 whereas mgo 7 was derived from rabbits immunised with a mixture of mr 311 and mr 336 the sequence of the peptides used to generated the polyclonal antibodies is shown below with their reference within the amino acid sequence of full length human ecsm4 as shown in fig1 the magic roundabout est sequence identified in the bioinformatics search for endothelial specific transcripts was used to isolate a cdna of 3800 base pairs in length from a human heart cdna library a screen using gene specific primers showed the gene to be present in libraries from heart adult and foetal brain liver lung kidney muscle placenta and small intestine but absent from peripheral blood leukocytes spleen and testis highest expression was in the placental library comparison of the magic roundabout sequence to that of roundabout revealed a transmembrane protein with homology throughout but absence of some extracellular domains thus mr has two immunoglobulin and two fibronectin domains in the extracellular domain compared to five immunoglobulin and two.