| Modification Notes |
There are two genes that express different HSFY proteins, designated HSFY1 and HSFY2, which are thought to be nearly identical. Both HSFY (heat shock transcription factor, Y-linked) proteins are also known as HSF2L (heat shock transcription factor 2-like protein) and are 401 amino acids in length, expressed in testis, present in Sertoli and spermatogenic cells and localized to the cytoplasm and nucleus. HSFY proteins belong to the HSF (heat shock factor) family, which activate the transcription of heat shock proteins and contain an HSF-type DNA-binding domain. HSFY2 is active in two developmental pathways, embryogenesis and spermatogenesis, and is highly expressed. HSFY2 may regulate the promoter of many genes from the HSP 70 gene family, thus regulating their expression and the expression of many germ cell proteins. During spermatogenesis, HSFY proteins are translocated from the cytoplasm to the nucleus. In Sertoli cell-only syndrome, HSFY proteins are only localized to the cytoplasm. AZFs (azoospermic factors), such as AZFb, are regions on the long arm of chromosome Y that, when deleted, are thought to be involved in male azoospermia. A region of DNA that encodes a part of the genes of both HSFY1 and HSFY2 is located on the AZFb region on chromosome Y and, as such, may be involved in male fertility. Mouse Hsfy2 is the functional ortholog of human HSFY1 and is expressed specifically in round spermatids, while the two human HSFY proteins are expressed in both round spermatids and spermatogonia. |
