Region-specific enrichment of proteins unique to each segment and organized by GO categories related to cell location.

<p>Enriched categories are color-coded: caput (red), corpus (green) and corpus (blue) indicating the general overall differences in these protein datasets. The darker the node, the greater enrichment in the indicated categories. White, or gray-colored nodes indicate no specific enrichment between each of the three protein lists.</p

Enriched immune system process GO categories for proteins in the caput and cauda sperm proteomes.

<p>Network immune system process diagram depicting GO categories enriched in the caput (blue) and cauda (magenta) sperm proteomes. The darker the node color, the stronger the enrichment while white nodes indicate an equal abundance of that functional category in the list of added and removed proteins.</p

Comparison of top 20 caudaSP proteins (by spectral counts) to the caputSP and corpusSP.

<p>*Rank of protein for each list is given in parentheses.</p><p>Comparison of top 20 caudaSP proteins (by spectral counts) to the caputSP and corpusSP.</p

Top 20 proteins in the caputSP, corpusSP and caudaSP by spectral count.

<p>Top 20 proteins in the caputSP, corpusSP and caudaSP by spectral count.</p

Sperm Proteome Maturation in the Mouse Epididymis

<div><p>In mammals, transit through the epididymis, which involves the acquisition, loss and modification of proteins, is required to confer motility and fertilization competency to sperm. The overall dynamics of maturation is poorly understood, and a systems level understanding of the complex maturation process will provide valuable new information about changes occurring during epididymal transport. We report the proteomes of sperm collected from the caput, corpus and cauda segments of the mouse epididymis, identifying 1536, 1720 and 1234 proteins respectively. This study identified 765 proteins that are present in sperm obtained from all three segments. We identified 1766 proteins that are potentially added (732) or removed (1034) from sperm during epididymal transit. Phenotypic analyses of the caput, corpus and cauda sperm proteomes identified 60 proteins that have known sperm phenotypes when mutated, or absent from sperm. Our analysis indicates that as much as one-third of proteins with known sperm phenotypes are added to sperm during epididymal transit. GO analyses revealed that cauda sperm are enriched for specific functions including sperm-egg recognition and motility, consistent with the observation that sperm acquire motility and fertilization competency during transit through the epididymis. In addition, GO analyses revealed that the immunity protein profile of sperm changes during sperm maturation. Finally, we identified components of the 26S proteasome, the immunoproteasome, and a proteasome activator in mature sperm.</p></div

Enriched biological process GO categories for proteins added and removed from sperm during epididymal transit.

<p>Network biological process diagram indicating functional enrichment of GO categories for proteins added (green) and removed (red) from sperm during epididymal transit. Color legend at top indicates range of overlap shared by the datasets. The varying shades of color represent nodes and clusters of functional GO categories biased towards proteins added (green) or removed (removed) during transit through the epididymis.</p

Mouse caput, corpus and cauda sperm proteins with known associated sperm phenotypes.

<p>^aProteins found to be added to sperm during epididymal transit in this study are indicated in <b>bold</b>.</p><p>Mouse caput, corpus and cauda sperm proteins with known associated sperm phenotypes.</p

GO term enrichment in proteins added during epididymal transit^a.

<p>^aCytoscape was used to identified enriched protein groups compared to proteins identified as "removed" (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140650#pone.0140650.g002" target="_blank">Fig 2</a>).</p><p>GO term enrichment in proteins added during epididymal transit<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140650#t005fn001" target="_blank">^a</a>.</p

Summary of Mass Spectrometry Results.

<p>Summary of Mass Spectrometry Results.</p

The β-defensins identified in the mouse sperm proteome.

<p>Segments of the epididymis and associated protein identified and regions of highest gene expression (based on transcriptional data from the mouse & rat) are shown. Known human orthologs and sperm functions are indicated.</p><p>¹ 1:1 ortholog</p><p>² 1:1 ortholog, apparent</p><p>³ 1:many ortholog</p><p>⁴ Possible ortholog</p><p>The β-defensins identified in the mouse sperm proteome.</p