p23 is a highly conserved ubiquitous protein, known to have an important function as a cochaperone for the
hsp90 chaperoning system (1). Studies have revealed that
p23 is a small protein (18 to 25 kDa) with a simple
structure (2, 3). p23 is a phosphor-protein, which is highly
acidic and has an aspartic acid-rich c-terminal domain
(1). Numerous studies have found p23 to be associated
with other client proteins like Fes tyrosine kinase (4), the
heme regulated kinase HRI (5), hsf1 transcription factor
(4), aryl hydrocarbon receptor (4), telomerase (6), and
Hepadnavirus reverse transcriptase (7). In spite of several
years of study, the exact functional significance of p23 is
still not clear (8). p23 is thought to be involved in the
adenosine triphosphatemediated hsp90 binding of client
proteins (8). Since many hsp90 client proteins are
involved in oncogenic survival signaling, a recent study
has concluded p23 to be a promising target in leukemic
apoptosis (9). Hsp90 and its co-chaperone p23 are certainly
among the emerging anti-tumor targets in oncology.
Specifically TSP23 (transcript similar p23) displays 44% and
17% amino acid identity with p23 and Sba1p respectively
(10).