Human RING finger protein ZNF645 is a novel testis-specific E3 ubiquitin ligase

A large number of testis-specific genes are involved in the complex process of mammalian spermatogenesis. Identification of these genes and their roles is important for understanding the mechanisms underlying spermatogenesis. Here we report on a novel human RING finger protein, ZNF645, which contains a C3HC4 RING finger domain, a C2H2 zinc-finger domain, and a proline-rich region, indicating that it has a structure similar to that of the c-Cbl-like protein Hakai. ZNF645 was exclusively expressed in normal human testicular tissue. Immunohistochemical analysis confirmed that ZNF645 protein was present in spermatocytes, round and elongated spermatids, and Leydig cells. Immunofluorescence staining of mature sperms further showed that the ZNF645 protein was localized over the postacrosomal perinuclear theca region and the entire length of sperm tail. An in vitro ubiquitination assay indicated that the RING finger domain of the ZNF645 protein had E3 ubiquitin ligase activity. Therefore, we suggest that ZNF645 might act as an E3 ubiquitin-protein ligase and play a role in human sperm production and quality control.

植物非生物逆境胁迫相关RING finger蛋白

RING finger蛋白是锌指蛋白类中一个庞大的蛋白家族,已成为拟南芥第三大蛋白家族,在水稻中也发现了488个。最典型的结构特点是序列内包含环指结构域(RING finger domain)。RING finger蛋白主要通过泛素化途径参与到植物细胞的生理生化过程。介绍了植物RING finger蛋白的结构特点和分类,综述它们的亚细胞定位,重点阐述它们在响应干旱胁迫、温度胁迫和盐胁迫等非生物逆境胁迫的调控作用。