The Evolutionary History of Prosaposin: Two Successive Tandem-Duplication Events Gave Rise to the Four Saposin Domains in Vertebrates

Abstract

Prosaposin is a multifunctional protein encoded by a single-copy gene. It contains four saposin domains (A, B, C, and D) occurring as tandem repeats connected by linker sequences. Because the saposin domains are similar to one another, it is deduced that they were created by sequential duplications of an ancestral domain. There are two types of evolutionary scenarios that may explain the creation of the four-domain gene: (1) two rounds of tandem internal gene duplication and (2) three rounds of duplications. An evolutionary and phylogenetic analysis of saposin DNA and amino acid sequences from human, mouse, rat, chicken, and zebrafish indicates that the first evolutionary scenario is the most likely. Accordingly, an ancestral saposin-unit duplication produced a two-domain gene, which, subsequently, underwent a second complete tandem duplication to give rise to the present four-domain structure of the prosaposin gene.

Identification of testis-relevant genes using in silico analysis from testis ESTs and cDNA microarray in the black tiger shrimp (Penaeus monodon)

“…Moreover, there are variable numbers of SapB domains in invertebrates, from 6 domains present in the pea aphid, Acyrthosiphon pisum (Homoptera), to up to 9 domains in the black legged tick Ixodes scapularis (Acari) and Nasonia vitripennis (Hymenoptera) (Figure 6B). Additional SapB domains in invertebrate saposins may be explained by several rounds of tandem internal gene duplication as previously proposed for the creation of the four domain saposins in vertebrate [35]. …”

Prosaposin Deficiency - a Rarely Diagnosed, Rapidly Progressing, Neonatal Neurovisceral Lipid Storage Disease. Report of a Further Patient

“…Their mechanisms of action appear to differ and can involve interactions with sphingolipids [6,40,45], phospholipid membranes [6,33,45], or the sphingolipid degrading lysosomal enzyme, itself [33,34,41]. The different functions of the Sap polypeptides, which are appreciably homologous to each other [18,33], are not yet fully understood.…”

Distribution of Prosaposin mRNA in the Central Nervous System of the Pigeon (Columba livia)

“…The deduced amino acid sequence of pigeon prosaposin shows a high‐degree similarity in amino acids between the avian and mammalian prosaposins. The predicted amino acid sequence of the pigeon has 93% identity to the chicken prosaposin (Cohen et al., ) and a 60, 48 and 49% identity to the human (Kondoh et al., ), rat (Hazkani‐Covo et al., ) and mouse (Kozak et al., ) prosaposins, respectively. In contrast, chicken prosaposin (Cohen et al., ) shows 56, 48 and 49% identity to the human (Kondoh et al., ), rat (Hazkani‐Covo et al., ) and mouse (Kozak et al., ) prosaposins, respectively.…”

“…The deduced amino acid sequences of pigeon prosaposin were aligned with the amino acid sequences of prosaposin proteins from various animals, and neighbour‐joining (N‐J) trees were constructed by using the ClustalW program (Thompson et al., ). The following sequences were used for prosaposins: chicken prosaposin (Cohen et al., ), human prosaposin (Kondoh et al., ), cattle prosaposin (Sano et al., ), dog prosaposin (), rat prosaposin (Hazkani‐Covo et al., ), mouse prosaposin (Kozak et al., ).…”