PCNA BINDING THROUGH A CONSERVED MOTIF

Proliferating cell nuclear antigen (PCNA) has recently been identified as a target for the binding of several proteins. The cell cycle regul atory protein, p21, and the replication endonuclease, Fen1, have alrea dy been described as competing for PCNA binding. Two recent reports ha ve identified DNA (cytosine-5)methyltransferase (MCMT) and the DNA rep air endonuclease XPG as binding to PCNA.(1,2) The remarkable thing abo ut these interactions is that they all seem to occur through a conserv ed motif that is likely to contact the same site on PCNA, This has fas cinating implications for a regulatory network linking these diverse p rotein functions. BioEssays 20: 195-199, 1998. (C) 1998 John Wiley & S ons, Inc.