AMID: new insights on its intracellular localization and expression at apoptosis

AMID ((a) under bar poptosis-inducing factor (AIF)-like (m) under bar itochondrion-associated (i) under bar nducer of (d) under bar eath) is a poorly studied member of the AIF family; despite the given name AMID, predicting its association with mitochondria, its real cellular localization, as well as its role and changes during apoptosis are currently unclear. By means of MALDI-TOF mass spectrometry, we have identified as AMID (accession number AAH38129, sequence coverage 31%) the protein isolated by Pisum sativum lectin-affinity chromatography from the plasma membrane fraction of apoptotic murine leukemia L1210 cells, lacking in the intact cells. The obtained results suggest its possible glycosylation that was further suggested by finding N-glycosylation sequon in the signal peptide of AMID protein (in silica), and by predicting transmembrane localization of its N-terminal part. Using monoclonal antibodies to AMID, we demonstrated an increased expression of AMID in human leukemia Jurkat T-cells after apoptosis induction. Immunocytochemical study suggested its association to the plasma membrane.