Subcellular localization of adenosine kinase in mammalian cells: The long isoform of AdK is localized in the nucleus

XA Cui, B Singh, J Park, RS Gupta - Biochemical and biophysical research …, 2009 - Elsevier
XA Cui, B Singh, J Park, RS Gupta
Biochemical and biophysical research communications, 2009Elsevier
Two isoforms of adenosine kinase (AdK) have been identified in mammalian organisms with
the long isoform (AdK-long) containing extra 20–21 amino acids at the N-terminus (NTS).
The subcellular localizations of these isoforms are not known and they contain no
identifiable targeting sequence. Immunofluorescence labeling of mammalian cells
expressing either only AdK-long or both isoforms with AdK-specific antibody showed only
nuclear labeling or both nucleus and cytoplasmic labeling, respectively. The AdK-long and …
Two isoforms of adenosine kinase (AdK) have been identified in mammalian organisms with the long isoform (AdK-long) containing extra 20–21 amino acids at the N-terminus (NTS). The subcellular localizations of these isoforms are not known and they contain no identifiable targeting sequence. Immunofluorescence labeling of mammalian cells expressing either only AdK-long or both isoforms with AdK-specific antibody showed only nuclear labeling or both nucleus and cytoplasmic labeling, respectively. The AdK-long and -short isoforms fused at the C-terminus with c-myc epitope also localized in the nucleus and cytoplasm, respectively. Fusion of the AdK-long NTS to green fluorescent protein also resulted in its nuclear localization. AdK-long NTS contains a cluster of conserved amino acids (PKPKKLKVE). Replacement of KK in this sequence with either AA or AD abolished its nuclear localization capability, indicating that this cluster likely serves as a nuclear localization signal. AdK in nucleus is likely required for sustaining methylation reactions.
Elsevier