Fig. 5. Model for the organization of the end-replication machinery in the macronucleus of Euplotes. Telomeric sequences are bound to the nuclear matrix by an interaction of the telomere-binding protein (TEBP) with components of this structure. Similarly, the p43-telomerase complex (p43, TERT) is also bound to this structure. In the course of replication the interaction of telomeres with the nuclear matrix is resolved, and at this stage it may well be that the telomere-binding protein is replaced by a replication-specific binding protein (Carlson et al., 1997). In contrast, the enzymatic machinery stays bound to this structure during replication.