Enables kinase binding activity; pentosyltransferase activity; and protein serine/threonine kinase activator activity. Involved in several processes, including IRE1-mediated unfolded protein response; positive regulation of protein serine/threonine kinase activity; and protein ADP-ribosylation. Located in endoplasmic reticulum tubular network and nuclear envelope. [provided by Alliance of Genome Resources, Apr 2022]