The SPA17 gene contains 5 exons and 4 introns and was predicted to span over approximately 23 kb of the genomic DNA. The first exon is encodes solely the 5 untranslated sequence. The exon 2 encodes the first 51 amino acid residue. Exon 3 and 4 are only 71 and 87 bp length and contain coding region. Exon 5 contains stop codon and followed by 3 untranslated sequence. The size of introns 2, 3 and 4 were 5970, 10.235 and 2520 bp, respectively.

Two transcript variants encoding the same protein have been identified for SP17-1 gene. This variant which was named SP17-1A and SP17-1B, both cDNA encodes identical protein sequence and only differed in 5 UTR part. One hundred percent homology can be detected from the poly A tail up to SP17-1 position -62 for variant A and -31 for variant B.

There is one pseudogene, SP17-2 intronless gene has all the hallmark of retro-position giving rise to a pseudogene, located on chromosome 10. SP17-2 gene had 61 point mutations, 4 nucleotide insertions and 2 deletions leading to internal stop codons and frame shifts which do not result in ORF encoding a full-length SPA17 polypeptide.

The SPA17 consists of 151 amino acids corresponding to a molecular weight of 17.4 kDa. SPA17 protein indicated to have functional role in cell regulation by its calmodulin binding site located at its C-terminal end. The N-terminal end of SPA17, similar to human cyclic adenosine 3-5-monophosphate (cAMP)-dependent protein kinase type II regulatory subunits (RII), may facilitate dimmer formation. SPA17s central domain is necessary for heparin-binding and exhibits the greatest sequence divergence of all three domains. This region plays an important role in cell-cell and/or cell matrix recognition process and/or cell regulation, possibly via its interaction with extra cellular heparin sulfate.

The SPA17 expression was originally found to be expressed exclusively in the testis. Recently, this gene also found in other somatic tissues.

SPA17 is present throughout the cytoplasm and is particularly concentrated around the nucleus. Its also present on the surface of B-lymphocytes and granulocytes; T-lymphocytes and monocytes; most malignant B and T lymphocytes cell lines.

SPA17 is highly antigenic, testes specific antigen and known have function to bind sperm to the zona pellucida of the oocyte. In addition, SPA17 may also have an alternative role in highly proliferating and neoplastic cells, such as a mediator of signal transduction, protein synthesis and/or unregulated growth.

The homologues of SPA17 protein sequences were found from eutherian and marsupial mammals, including rat, mouse, macaque, baboon, human, marmoset, rabbit, Monodelphis and wallaby.