Sperm-associated antigen 1 explained

Sperm-associated antigen 1 is a protein that in humans is encoded by the SPAG1 gene.^{[1] [2]}

Function

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.

Further reading

• Diekman AB, Herr JC . Sperm antigens and their use in the development of an immunocontraceptive . American Journal of Reproductive Immunology . 37 . 1 . 111–7 . January 1997 . 9138444 . 10.1111/j.1600-0897.1997.tb00199.x . 39710127 .
• Zhang ML, Wang LF, Miao SY, Koide SS . Isolation and sequencing of the cDNA encoding the 75-kD human sperm protein related to infertility . Chinese Medical Journal . 105 . 12 . 998–1003 . December 1992 . 1299558 .
• Bonaldo MF, Lennon G, Soares MB . Normalization and subtraction: two approaches to facilitate gene discovery . Genome Research . 6 . 9 . 791–806 . September 1996 . 8889548 . 10.1101/gr.6.9.791 . free .
• Takaishi M, Huh N . A tetratricopeptide repeat-containing protein gene, tpis, whose expression is induced with differentiation of spermatogenic cells . Biochemical and Biophysical Research Communications . 264 . 1 . 81–5 . October 1999 . 10527845 . 10.1006/bbrc.1999.1477 .
• Lin W, Zhou X, Zhang M, Li Y, Miao S, Wang L, Zong S, Koide SS . Expression and function of the HSD-3.8 gene encoding a testis-specific protein . Molecular Human Reproduction . 7 . 9 . 811–8 . September 2001 . 11517287 . 10.1093/molehr/7.9.811 . free .
• Ficarro S, Chertihin O, Westbrook VA, White F, Jayes F, Kalab P, Marto JA, Shabanowitz J, Herr JC, Hunt DF, Visconti PE . Phosphoproteome analysis of capacitated human sperm. Evidence of tyrosine phosphorylation of a kinase-anchoring protein 3 and valosin-containing protein/p97 during capacitation . The Journal of Biological Chemistry . 278 . 13 . 11579–89 . March 2003 . 12509440 . 10.1074/jbc.M202325200 . free .
• Kanazawa R, Komori S, Sakata K, Tanaka H, Sawai H, Tsuji Y, Koyama K . Isolation and characterization of a human sperm antigen gene h-Sp-1 . International Journal of Andrology . 26 . 4 . 226–35 . August 2003 . 12846798 . 10.1046/j.1365-2605.2003.00418.x .
• Neesse A, Gangeswaran R, Luettges J, Feakins R, Weeks ME, Lemoine NR, Crnogorac-Jurcevic T . Sperm-associated antigen 1 is expressed early in pancreatic tumorigenesis and promotes motility of cancer cells . Oncogene . 26 . 11 . 1533–45 . March 2007 . 16983343 . 10.1038/sj.onc.1209961 . 1103473 .

Notes and References

1. Liu N, Qiao Y, Cai C, Lin W, Zhang J, Miao S, Zong S, Koide SS, Wang L . A sperm component, HSD-3.8 (SPAG1), interacts with G-protein beta 1 subunit and activates extracellular signal-regulated kinases (ERK) . Frontiers in Bioscience . 11 . 1679–89 . May 2006 . 16368546 . 10.2741/1913 . free .
2. Web site: Entrez Gene: SPAG1 sperm associated antigen 1.