s48_45 Sexual stage antigen s48/45 domain
SMART ACC:	SM000970
Description:	This family contains sexual stage s48/45 antigens from Plasmodium (approximately 450 residues long). These are surface proteins expressed by Plasmodium male and female gametes that have been shown to play a conserved and important role in fertilisation (PUBMED:11163248).
InterPro ACC:	IPR010884
InterPro abstract:	This entry represents the 6-Cys domain. The 6-Cysteine (6-Cys) domain is found in Plasmodium proteins that are expressed in all stages of the parasite life cycle in both the vertebrate and mosquito hosts. The domain is of roughly 120 amino acids and contains six positionally conserved cysteines. It might occur in 1-14 copies per protein, either as the sole globular domain or in combination … expand This entry represents the 6-Cys domain. The 6-Cysteine (6-Cys) domain is found in Plasmodium proteins that are expressed in all stages of the parasite life cycle in both the vertebrate and mosquito hosts. The domain is of roughly 120 amino acids and contains six positionally conserved cysteines. It might occur in 1-14 copies per protein, either as the sole globular domain or in combination wih β-helix-forming hexapeptide repeats as is the case of sequestrin. It is generally found in tandem pairs of A-type and B-type domains. Previously believed to be exclusive to Plasmodium, the 6-Cys domain also exists in proteins found in all members of the aconoidasidan (hematozoan) clade of Apicomplexa, which unites the haemosporidians (Plasmodium) and piroplasms) [ PUBMED:11163248 PUBMED:16155126 PUBMED:20386715 PUBMED:22493233 PUBMED:23511632 ]. The 6-cys domain is a β-sandwich formed by two sheets with a mixture of parallel and antiparallel strands. Three disulfide bonds are present in the 6_Cys domain with C1-C2, C3-C6, and C4-C5 connectivity. C1-C2 and C3-C6 pin together the two sheets of the β-sandwich, whereas C4-C5 links an ancyllary loop to the core domain [ PUBMED:22493233 PUBMED:23511632 ]. Some Plasmodium proteins known to contain a 6-Cys domain are listed below: Pfs48/45, involved in male/female gamete fusion in the mosquito midgut. It is predicted to be glycosylphosphatidylinositol (GPI)-anchored to the gamete surface. Pfs230, involved in male/female gamete fusion in the mosquito midgut. It is a soluble protein that associates with the gamete membrane by binding to Pfs48/45. Pfs47, involved in male/female gamete fusion in the mosquito midgut. It is found on female gametes. P52, expressed in the sporozoite. May be required for invasion of hepatocytes and to promote normal development in the liver. P36, expressed in the sporozoite. May be required for invasion of hepatocytes and to promote normal development in the liver. Pf41, located on the surface of merozoites and has a signal sequence. Pf38, located on the surface of merozoites. It has a signal sequence and is GPI-anchored to the merozoite surface. Pf12, located on the surface of merozoites. It has a signal sequence and is GPI-anchored to the merozoite surface. Pf92, located on the surface of merozoites. It has a signal sequence and is GPI-anchored to the merozoite surface. collapse
Family alignment:	View the Family alignment or the Alignment consensus sequence
There are 1 287 s48_45 domains in 509 proteins in SMART's NRDB database.

Taxonomic distribution of proteins containing s48_45 domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing s48_45 domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Predicted cellular role

Cellular role:	Interaction (with the environment)

Relevant references for this domain

Primary literature for the s48_45 domain is listed below. Automatically-derived, secondary literature is also available.

KEGG pathways involving proteins which contain this domain

This information is based on the mapping of SMART genomic protein database to KEGG orthologous groups. Percentages are related to the number of proteins containing a s48_45 domain which could be assigned to a KEGG orthologous group, and not all proteins containing s48_45 domains. Please note that proteins can be included in multiple pathways, ie. the numbers below will not add to 100%.

KEGG pathways

Some of these pathways are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

KEGG orthologous groups

Some of these KOs are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

3D structures in PDB containing this domain

Links to other resources describing this domain

Pfam	s48_45
InterPro	IPR010884