The SRY protein is a crucial factor in determining male sex characteristics in mammals. It is encoded by the SRY gene, located on the Y chromosome. This protein initiates the development of testes, which produce male hormones, leading to the formation of male physical traits. In the absence of the SRY protein, the default developmental pathway leads to female characteristics. The presence of SRY triggers a cascade of genetic events that promote male differentiation. Understanding the role of SRY is essential in fields like genetics and reproductive biology, as it helps explain sex determination processes.