Identification of a Novel Testis-Specific Member of the Phosphatidylethanolamine Binding Protein Family, pebp-21

Abstract

The phosphatidylethanolamine binding proteins (pebps) are an evolutionarily conserved family of proteins recently implicated in mitogen-activated protein (MAP) kinase pathway regulation, where they are called raf kinase inhibitory proteins. Here, we describe the cloning, cellular localization, and partial characterization of a new member, pebp-2, with potential roles in male fertility. Expression data show that pebp-2 is a testis-specific 21-kDa protein found within late meiotic and haploid germ cells in a stage-specific pattern that is temporally distinct from that of pebp-1. Sequence analyses suggest that pebp-2 forms a distinct subset of the pebp family within mammals. Database analyses revealed the existence of a third subset. Analysis suggests that the specificity/regulation of the distinct pebps subsets is likely to be determined by the amino terminal 40 amino acids or the 3' untranslated region, where the majority of sequence differences occur. Protein homology modeling suggests that pebp-2 protein is, however, topologically similar to other pebps and composed of Greek key fold motifs, a dominant beta-sheet formed from five anti-parallel beta strands forming a shallow groove associated with a putative phosphatidylethanolamine binding site. The pebp-2 gene is intronless and data suggest that it is a retrogene derived from pebp-1. Further, pebp-2 colocalizes with members of the MAP kinase pathway in late spermatocytes and spermatids and on the midpiece of epididymal sperm. These data raise the possibility that pebp-2 is a novel participant in the MAP kinase signaling pathway, with a role in spermatogenesis or posttesticular sperm maturation.

A Novel Human Phosphatidylethanolamine-binding Protein Resists Tumor Necrosis Factor α-induced Apoptosis by Inhibiting Mitogen-activated Protein Kinase Pathway Activation and Phosphatidylethanolamine Externalization

“…According to O'Bryan and colleagues (10), previously identified PEBPs can be grouped into three subfamilies; the majority of differences between these subfamilies are in the N-terminal residues (those preceding the PE-binding domain), especially the first 10 amino acids. Members of the three subfamilies share similar overall features, including length (each being ϳ190 residues) and amino acid composition in functional domains.…”

“…Mapping of the binding domains has shown that MEK and Raf-1 bind to overlapping sites in hPEBP1, whereas MEK and hPEBP1 associate with different domains in Raf-1, and Raf-1 and hPEBP1 bind to different sites in MEK. In addition, mPEBP2, a recently characterized novel testis-specific member of the phosphatidylethanolamine-binding protein family, colocalizes with members of the mitogen-activated protein kinase pathway in late spermatocytes and spermatids and on the midpiece of epididymalsperm (10).…”

Proteomic Analysis of Membrane-Associated Proteins from Rat Liver Autophagosomes

“…54 Its expression is particularly high in liver and testis; 55 the latter representing a tissue-specific isoform. 56 In the brain, an N-terminal fragment of PEBP known as the "hippocampal cholinergic neurostimulating peptide" (HCNP) seems to serve as a transmitter and an endocrine factor. 57 PEBP is primarily a cytosolic protein, but is able to bind to cellular and model membranes through its N-and C-terminal ends.…”

FGFR-1 signaling is involved in spermiogenesis and sperm capacitation

“…During the process of cloning components of the mouse sperm tail, as described previously (Hickox et al, 2002;O'Bryan et al, 1998), a partial fragment of suc1-associated neurotrophic factor target 2 (Snt-2) was identified. The missing 3Ј end was cloned using 3Ј rapid amplification of cDNA ends (RACE), utilizing the FirstChoice TM RLM-RACE kit (Ambion, Texas) as previously described (O'Bryan et al, 2000b;Troutt et al, 1992), using the primers F1701A 5Ј-AGC-CCAATGCACCTATGAG-3Ј, F1701B 5Ј-CTTCCTCCTGTGTGGGAGAG-3Ј and the supplied adaptor primer, AP3Ј.…”