This gene encodes a bi-functional protein. In the cytoplasm, the encoded protein binds the cytoplasmic tail of human surface antigen CD2 via its C-terminal GYF domain, and regulate CD2-triggered T lymphocyte activation. In the nucleus, this protein is a component of the U5 small nuclear ribonucleoprotein complex and is involved in RNA splicing. A pseudogene has been identified on chromosome 7. Alternative splicing results in multiple transcript variants but their biological validity has not been determined.