Reverse‐phase high‐performance liquid chromatography of nerve growth factor receptor‐like proteins identified with monoclonal antibodies

Human neuroblastoma SK‐N‐SH‐SY5Y (SY5Y) and rat pheochromocytoma PC12 cells are model cell lines used in the study of nerve growth factor (NGF) effect. The effects of NGF are initiated by binding to cell surface receptors (NGFR). The amino acid sequence for NGFR has been deduced based on the identification of a single gene for NGFR. However, there are two kinds of NGF binding activities and several reported molecular weights of NGFR. We report here on the demonstration of NGFR‐like proteins from PC12 and SY5Y cells by sequential lectin chromatography, reverse‐phase HPLC, and SDS‐PAGE analysis of immunoprecipitates obtained with NGFR‐specific monoclonal antibodies. For both human and rodent NGFR, there was a tendency for the higher molecular‐ weight species of NGFR‐like proteins to be eluted in more hydrophobic fractions. Also, the expression of different species of NGFR could be modified by treatment with retinoic acid (RA). These results are consistent with the hypothesis that the different molecular species of NGFR may result from the generation of a truncated form of NGFR, the presence of sugar residues on the NGFR protein, dimer formation between NGFR, or the association of NGFR with a receptor‐ associated protein.