Fig. 1. (a) 2D electron microscopic images of the CSN and the LID. The putative subunit arrangement of the CSN on the basis of the subunit-subunit interaction studies (Kapelari et al., 2000) is indicated. LID subunit-subunit interactions were deduced from CSN data by arranging homologous subunits. The central groove is marked by black arrow. The images were provided by B. Kapelari. (b) CSN interactions with other proteins. The CSN model is based on the electron microscopic image shown in (a) and on subunit-subunit interaction studies summarised recently (Kapelari et al., 2000). Subunits containing MPN domains are blue and those with PCI domains are yellow. The phosphorylation of CSN2 and CSN7 is indicated. All interactions of CSN subunits with other proteins are referenced in Table 1.