| The pp32 (ANP32) gene family contains at least 4 closely related members—pp32, pp32r1, pp32r2, and April. Although the transcripts and proteins encoded by the members are highly identical in nucleotide and amino acid sequences, they possess discrete and seemingly contrasting functions. pp32, the predominantly expressed member of this family, plays a role in chromatin remodeling, messenger RNA stability, caspase-independent apoptosis, inhibition of protein phosphatase, 2A activity, and inhibition of transformation (Chen et al., 1996; Li et al., 1996b; Brennan et al., 2000; Beresford et al., 2001; Cervoni et al., 2002).; The predicted structure of the nuclear phosphoprotein pp32 is suggestive of a multi-functional molecule in cellular processes. The amino acid sequence of pp32, encoded on chromosome 15, translates into structural elements that correlate with functional biology. pp32 is a highly conserved protein that has an N-terminal alpha-helical domain, which contains a putative leucine zipper and nuclear localizations, and a carboxyl acidic domain that comprises the last third of the molecule. pp32's structural attributes in relation to its biology are elucidated herein.; Clinically, pp32 is expressed in cancer and undifferentiated cells. In cancerous tissues, the pp32 that is expressed has been found to contain no mutations to date (Kadkol et al., 1999; Kadkol et al., 2001). Work performed in the laboratory over the last decade has elucidated the role of pp32 in the processes of transformation and tumorigenesis (Brody et al., 1999; Bai et al., 2001). Other groups have discovered human pp32 in a number of different contexts with cooperating proteins (see table IIb, v.i.). The official, NCBI nomenclature for pp32 is ANP32A, which stands for Acidic Leucine-Rich Nuclear Phosphoprotein 32 Family, Member A (www.ncbi.nlm.nih.gov). Although pp32 has been described functionally in these settings, signal transduction pathways involving pp32 have only recently become clear with data presented herein. Also, the first report of pp32's effect on the mechanisms underlying differentiation is reported in this manuscript. |
