The ePHD ("extended plant homeodomain") zinc finger is characterized as Cys2HisCys5HisCys2His. This entry represents the ePHD finger of Jade-2. Jade-2 is a homeodomain (PHD) zinc finger protein that is closely related to Jade-1, which functions as an essential regulator of multiple cell signaling pathways. Like Jade-1, Jade-2 is required for ING4 and ING5 to associate with histone acetyltransferase (HAT) HBO1 and Eaf6 to form a HBO1 complex that has a histone H4-specific acetyltransferase activity, a reduced activity toward histone H3, and is responsible for the bulk of histone H4 acetylation in vivo. Jade-2 contains a canonical PHD finger followed by this non-canonical ePHD finger, both of which are zinc-binding motifs [, ].
Jade-2, also termed PHD finger protein 15 (PHF15), is a PHD ("plant homeodomain") zinc finger protein that is closely related to Jade-1, which functions as an essential regulator of multiple cell signaling pathways. Like Jade-1, Jade-2 is required for ING4 and ING5 to associate with histone acetyltransferase (HAT) HBO1 and Eaf6 to form a HBO1 complex that has a histone H4-specific acetyltransferase activity, a reduced activity toward histone H3, and is responsible for the bulk of histone H4 acetylation in vivo. Jade-2 contains a canonical Cys4HisCys3 PHD finger followed by a non-canonical extended PHD (ePHD) finger, Cys2HisCys5HisCys2His, both of which are zinc-binding motifs. This entry represents the canonical Cys4HisCys3 PHD finger [, ].
Jade-3, also termed PHD finger protein 16 (PHF16), is a PHD ("plant homeodomain") zinc finger protein that is closely related to Jade-1, which functions as an essential regulator of multiple cell signaling pathways. Like Jade-1, Jade-3 is required for ING4 and ING5 to associate with histone acetyl transferase (HAT) HBO1 and Eaf6 to form a HBO1 complex that has a histone H4-specific acetyltransferase activity, a reduced activity toward histone H3, and is responsible for the bulk of histone H4 acetylation in vivo. Jade-3 contains a canonical Cys4HisCys3 PHD domain followed by a non-canonical extended PHD (ePHD) domain, Cys2HisCys5HisCys2His, both of which are zinc-binding motifs. This model corresponds to the canonical Cys4HisCys3 PHD finger [, ].
Jade-1 is a novel binding partner of von Hippel-Lindau (VHL) tumour suppressor Pvhl, a key regulator of the cellular oxygen sensing pathway []. It is highly expressed in renal proximal tubules. Jade-1 functions as an essential regulator of multiple cell signaling pathways. It may be involved in the serine/threonine kinase AKT/AKT1 pathway during renal cancer pathogenesis and normally prevents renal epithelial cell proliferation and transformation []. It also acts as a pro-apoptotic and growth suppressive ubiquitin ligase to inhibit canonical Wnt downstream effector beta-catenin for proteasomal degradation [, ], and as a transcription factor associated with histone acetyltransferase activity and with increased abundance of cyclin-dependent kinase inhibitor p21 []. Moreover, Jade-1 is required for ING4 and ING5 to associate with histone acetyltransferase (HAT) HBO1 and Eaf6 to form a HBO1 complex, and plays a role in epithelial cell regeneration []. It has also been identified as a novel component of the nephrocystin protein (NPHP) complex and interacts with the ciliary protein nephrocystin-4 (NPHP4) []. Jade-1 contains a canonical Cys4HisCys3 PHD ("plant homeodomain") finger followed by a non-canonical extended PHD (ePHD) finger, Cys2HisCys5HisCys2His, both of which are zinc-binding motifs. This model corresponds to the canonical Cys4HisCys3 PHD finger [].
