SPAG1

The correlation of anti-sperm antibodies with cases of unexplained infertility implicates a role for these antibodies in blocking fertilization. Improved diagnosis and treatment of immunologic infertility, as well as identification of proteins for targeted contraception, are dependent on the identification and characterization of relevant sperm antigens. The protein expressed by this gene is recognized by anti-sperm agglutinating antibodies from an infertile woman. Furthermore, immunization of female rats with the recombinant human protein reduced fertility. This protein localizes to the plasma membrane of germ cells in the testis and to the post-acrosomal plasma membrane of mature spermatozoa. Recombinant polypeptide binds GTP and exhibits GTPase activity. Thus, this protein may regulate GTP signal transduction pathways involved in spermatogenesis and fertilization. Two transcript variants of this gene encode the same protein.

Full Name

Sperm Associated Antigen 1

Function

May play a role in the cytoplasmic assembly of the ciliary dynein arms (By similarity).
May play a role in fertilization. Binds GTP and has GTPase activity.

Biological Process

Biological Process axonemal dynein complex assemblyISS:UniProtKB
Biological Process protein stabilization1 PublicationIC:ComplexPortal
Biological Process single fertilizationManual Assertion Based On ExperimentTAS:ProtInc

Cellular Location

Cytoplasm
Dynein axonemal particle
Colocalizes with tubulin.

Involvement in disease

Ciliary dyskinesia, primary, 28 (CILD28):
A disorder characterized by abnormalities of motile cilia. Respiratory infections leading to chronic inflammation and bronchiectasis are recurrent, due to defects in the respiratory cilia. Patients may exhibit randomization of left-right body asymmetry and situs inversus, due to dysfunction of monocilia at the embryonic node. Primary ciliary dyskinesia associated with situs inversus is referred to as Kartagener syndrome.