Proteins containing this p23_like domain include p23 and its Saccharomyces cerevisiae (Sc) homolog Sba1. Both are co-chaperones for the heat shock protein (Hsp) 90. p23 binds Hsp90 and participates in the folding of a number of Hsp90 clients, including the progesterone receptor. p23 also has a passive chaperoning activity and in addition may participate in prostaglandin synthesis. Both p23 and Sba1p can regulate telomerase activity. This group includes domains similar to the C-terminal CHORD-SGT1 (CS) domain of suppressor of G2 allele of Skp1 (Sgt1). Sgt1 interacts with multiple protein complexes and has the features of a co-chaperone. Human (h) Sgt1 interacts with both Hsp70 and Hsp90, and has been shown to bind Hsp90 through its CS domain. Saccharomyces cerevisiae (Sc) Sgt1 is a subunit of both core kinetochore and SCF (Skp1-Cul1-F-box) ubiquitin ligase complexes. Sgt1 is required for pathogen resistance in plants. This group also includes the p23_like domains of human butyrate-induced transcript 1 (hB-ind1), NUD (nuclear distribution) C, Melusin, and NAD(P)H cytochrome b5 (NCB5) oxidoreductase (OR). hB-ind1 plays a role in the signaling pathway mediated by the small GTPase Rac1, NUDC is needed for nuclear movement, Melusin interacts with two splice variants of beta1 integrin, and NCB5OR plays a part in maintaining viable pancreatic beta cells.