SPAG1
SPAG1 (sperm associated antigen 1, also known as SP75, HSD-3.8 and TPIS) is a GTP-binding protein with GTPase activity that may contribute to cytoplasmic assembly of ciliary dynein arms and to fertilisation. It belongs to the tetratricopeptide repeat domain and axonemal dynein assembly factor groups. Browse Assay Genie's current range of SPAG1 research reagents below, or read on for the biology behind the target.
SPAG1 may play a role in the cytoplasmic assembly of the ciliary dynein arms, and it may also play a role in fertilisation. The recombinant polypeptide binds GTP and exhibits GTPase activity, which led to the suggestion that the protein may regulate GTP signal transduction pathways involved in spermatogenesis and fertilisation. In cells, UniProt places the protein in the cytoplasm, in dynein axonemal particles.
The SPAG1 gene encodes sperm-associated antigen 1, and its two transcript variants encode the same protein. HGNC classifies it within the tetratricopeptide repeat domain containing group, the axonemal dynein assembly factors and the R2SP complex. In germ cells, the protein localises to the plasma membrane in the testis and to the post-acrosomal plasma membrane of mature spermatozoa. Mouse and rat both have a Spag1 ortholog.
SPAG1 was first characterised as a sperm antigen. Anti-sperm agglutinating antibodies from an infertile woman recognise the protein, and anti-sperm antibodies have been correlated with unexplained infertility through a proposed role in blocking fertilisation. Immunising female rats with the recombinant human protein reduced fertility. For this reason, SPAG1 is of interest for understanding immunological infertility and for identifying proteins for targeted contraception. Other symbols include SP75, HSD-3.8, TPIS, CT140, CILD28 and DNAAF13; the last two reflect its link to ciliary dynein assembly.
Anti-sperm antibodies from an infertile woman recognise SPAG1, making it relevant to diagnosing and treating immunologic infertility.
Immunising female rats with recombinant human SPAG1 reduced fertility, so it is studied as a candidate for targeted contraception.
SPAG1 may take part in cytoplasmic assembly of ciliary dynein arms and is classed among axonemal dynein assembly factors.
With its GTP-binding and GTPase activity, SPAG1 may regulate GTP signalling pathways involved in spermatogenesis and fertilisation.
SPAG1 may play a role in the cytoplasmic assembly of ciliary dynein arms and in fertilisation. It binds GTP and has GTPase activity, so it may regulate GTP signal transduction pathways involved in spermatogenesis and fertilisation. These functions are described as probable rather than established.
SPAG1 is also called sperm-associated antigen 1, SP75, FLJ32920, HSD-3.8, TPIS, CT140, CILD28 and DNAAF13. Two transcript variants of the gene encode the same protein, so there is a single protein sequence to consider.
Mouse and rat each have a Spag1 ortholog. SPAG1 is linked to immunologic infertility because anti-sperm antibodies recognise it, and the aliases CILD28 and DNAAF13 point to ciliary dynein assembly. Check the datasheet of any product for its validated reactivity.
Other sperm-associated antigen family members studied in fertilisation, spermatogenesis and germ cell biology.
Gene and protein annotations from HGNC, NCBI Gene and UniProt Q07617; product specifications from Assay Genie datasheets.