Evolution of the secretoglobins: a genomic and proteomic view

Abstract

Mouse salivary androgen‐binding protein (ABP) is a member of the newly erected secretoglobin family, no member of which has yet been assigned an indisputable function. We have suggested a role for ABP in mate selection behaviour and sexual isolation. Although this has been a particularly attractive hypothesis given the evidence for strong positive selection on its alpha subunit gene, Abpa, we have held out the possibility that there might be an as‐yet‐undiscovered primary function for ABP. This is particularly important in light of its membership in the secretoglobin family, and we are pursuing the broader issue of shared functions of the secretoglobins with genomic and bioinformatic studies. Here we present as complete a comparison as possible of the secretoglobins in the genomes of three species of mammals: mouse, rat and human, and we compare the protein sequences and their potential evolutionary relationships. We suggest that the secretoglobins can be divided into at least five families. In rodent and human genomes, these gene families are found in two main clusters that are syntenic between rat and mouse. Humans have only the three families that are found within the uteroglobin/clara cluster, because no ABP‐containing secretoglobin cluster has yet been identified. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84, 493–501.

High abundance of testosterone and salivary androgen-binding protein in the lateral nasal gland of male mice

“…Mouse sABPs are members of the secretoglobin family [33]. A functional sABP is a covalently linked (through a disulfide bond) heterodimer composed of one ABP α subunit (belonging to secretoglobin family B) and one ABP β or γ subunit (belonging to secretoglobin family E).…”

Diverse spatial, temporal, and sexual expression of recently duplicated androgen-binding protein genes in Mus musculus

“…Androgen-binding protein α subunit (ABPα) forms covalently linked heterodimers with either β or γ subunits, and these are secreted into the saliva following expression in the submaxillary gland. ABPα, ABPβ and ABPγ proteins are secretoglobins, a family of secreted proteins [23] that bind lipophilic ligands (for a review, see [24]) and are present in mammals and birds [25,26], but whose roles in cellular and physiological function all remain obscure [27,28]. …”

“…Much of the previous work on salivary ABP has focused on determining its function [22]; reviewed briefly in [25]. Laboratory tests of female preference for males carrying different genetic variants of salivary ABP have provided evidence that the protein may mediate sexual preference [29,30].…”

“…We chose organs and glands to obtain as wide a representation of gene expression in the mouse as possible. We specifically included any tissues where expression of other secretoglobins has been identified (Harderian gland, lacrimal gland, lung, kidney, uterus, skin/sebaceous glands, salivary glands and prostate; [25]). In the head we surveyed the brain and (separately) olfactory lobes, parotid glands, sublingual glands, submaxillary glands, lacrimal glands, major olfactory epithelium (MOE), vomeronasal organ (VNO) and Harderian glands; in the body, we tested skin, adrenal gland, heart, spleen, kidney, testis, lung, liver, pancreas, small intestine, bladder, prostate, ovary and uterus.…”

Comparative Evolutionary Genomics of Androgen-Binding Protein Genes

“…These are small, globular, secreted proteins whose phyletic distribution is currently restricted to the mammals and whose functions all remain elusive (Karn 1994;Klug et al 2000;Reynolds et al 2002;Laukaitis and Karn 2004). In laboratory experiments, female mice have demonstrated a significant mating preference for males with a comparable Abpa genotype (Laukaitis et al 1997;Talley et al 2001).…”