The mode of actions of glyceraldehyde-3-phosphate dehydrogenase identified as an immunoglobulin production stimulating factor.

Immunoglobulin production stimulating factor-II alpha, which enhances immunoglobulin production of human and mouse hybridomas was purified from cell lysate of human Burkitt's lymphoma, Namalwa cells, and identified as glyceraldehyde-3-phosphate dehydrogenase. The enhancement of immunoglobulin production with this enzyme was not linked with its enzymatic activity. The enzyme enhanced immunoglobulin productivity of transcription-suppressed hybridomas, but did not enhance that of translation-suppressed hybridomas. From these results, it is suggested that this enzyme takes part in the post-translational control or the enhancement of translation activity to stimulate immunoglobulin production of hybridomas.