RNA recognition motif (RRM) found in peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC-1-beta) and similar proteins
This subfamily corresponds to the RRM of PGC-1beta, also termed PPAR-gamma coactivator 1-beta, or PPARGC-1-beta, or PGC-1-related estrogen receptor alpha coactivator, which is one of the members of PGC-1 transcriptional coactivators family, including PGC-1alpha and PGC-1-related coactivator (PRC). PGC-1beta plays a nonredundant role in controlling mitochondrial oxidative energy metabolism and affects both, insulin sensitivity and mitochondrial biogenesis, and functions in a number of oxidative tissues. It is involved in maintaining baseline mitochondrial function and cardiac contractile function following pressure overload hypertrophy by preserving glucose metabolism and preventing oxidative stress. PGC-1beta induces hypertriglyceridemia in response to dietary fats through activating hepatic lipogenesis and lipoprotein secretion. It can stimulate apolipoprotein C3 (APOC3) expression, further mediating hypolipidemic effect of nicotinic acid. PGC-1beta also drives nuclear respiratory factor 1 (NRF-1) target gene expression and NRF-1 and estrogen related receptor alpha (ERRalpha)-dependent mitochondrial biogenesis. The modulation of the expression of PGC-1beta can trigger ERRalpha-induced adipogenesis. PGC-1beta is also a potent regulator inducing angiogenesis in skeletal muscle. The transcriptional activity of PGC-1beta can be increased through binding to host cell factor (HCF), a cellular protein involved in herpes simplex virus (HSV) infection and cell cycle regulation. PGC-1beta is a multi-domain protein containing an N-terminal activation domain, an LXXLL coactivator signature, a tetrapeptide motif (DHDY) responsible for HCF binding, two glutamic/aspartic acid-rich acidic domains, and an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). In contrast to PGC-1alpha, PGC-1beta lacks most of the arginine/serine (SR)-rich domain that is responsible for the regulation of RNA processing.