Zinc finger Y-chromosomal protein is a protein that in humans is encoded by the ZFY gene of the Y chromosome. This gene encodes a zinc finger-containing protein that may function as a transcription factor. This gene was once a candidate gene for the testis-determining factor (TDF) and was erroneously referred to as TDF. In humans, ZFY is most broadly expresses in the testis and prostate. However, 20 other tissues also express ZFY, such as esophagus, urinary bladder, bone marrow, small intestine, appendix and gall bladder.