Identification of defensins in human lymphocyte nuclei

The cell nucleus plays an essential role in all aspects of cell function an d regulation. Most of the nuclear proteins/ peptides are synthesized in the cytoplasm. and transported into the nucleus through the nuclear pore compl exes. The nuclear proteins/peptides conjugate with each other and interact in transcriptional activation/inactivation. Several of the high molecular m ass transcription factors (> 30 kDa) have been identified and-characterized . However, the information on the low molecular mass proteins/peptides of t he nucleus is limited. We have investigated these low molecular mass protei ns/peptides from the nucleus of human peripheral blood lymphocytes using re versed-phase high-performance liquid chromatography (RP-HPLC). The HPLC fra ctions were further analysed by matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry, electrospray ionization time of flight (ESI-TOF) mass spectrometry and: electrospray ionization fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry for mass d etermination. Using this combination of mass spectrometry techniques and mi crosequence analysis, we have shown that human, lymphocyte nuclei contain d efensins, a mixture of human neutrophil granule peptide 1, 2 and 3.