An unusually small (8 kD) protein (p8(MTCP-1)) is coded by the putativ
e oncogene MTCP-1 (also called c6.1B), involved in the translocation t
(X;14)(q28;q11) associated with some mature T-cell proliferations. Her
e, we show by subcellular fractionation and by confocal microscopy tha
t this protein is located in the mitochondria. This localization orien
tates toward a role of p8(MTCP-1) in the mitochondrial metabolism whic
h may be relevant for the oncogenic process.