Domain recognition of the ING1 tumor suppressor by a panel of monoclonal antibodies.

The inhibitor of growth (ING) family of proteins play key roles in cell cycle arrest, apoptosis, cell aging, and the DNA damage response. To date, several domains including the plant homeodomain (PHD), lamin interacting domain (LID), and nuclear localization sequence (NLS) have been identified in the ING family of proteins that contribute to their function. To better understand the functional attributes of the ING proteins, we have developed and further characterized a panel of monoclonal IgGs that we call CAbs 1-9 based on their recognition sites, strength of binding affinity, and their specificity for ING1. All of the nine CAbs recognize the C-terminal half of the p33ING1b protein, which is fully conserved among all ING1 isoforms, being encoded by a common exon. Two of the nine CAbs bind a fragment that includes the PHD, which is the most conserved domain among ING family proteins (ING1-5), and one CAb cross-reacts with all ING family proteins that are encoded by different genes. Five of the nine CAbs r...