Cloning of a Glucose Phosphate Isomerase/Neuroleukin-Like Sperm Antigen Involved in Sperm Agglutination1

Abstract

The mouse monoclonal antibody (mAb) A36 produced by us and shown to induce extensive, "tangled" sperm agglutination was used to isolate cDNAs encoding its cognate antigen. Three overlapping cDNA clones specifically recognized by the mAb were isolated from a human testis cDNA expression library in lambdagt11. Sequencing of these cDNAs yielded the complete nucleotide sequence of a 3-kilobase cDNA that encodes the mAb-related polypeptide, designated sperm antigen-36 (SA-36), composed of 558 deduced amino acids. SA-36 cDNA contained a 5' untranslated region of 234 nucleotides (nt), an open reading frame of 1674 nt, and a 3' untranslated region of 1138 nt. SA-36 cDNA displayed > 99% homology to glucose phosphate isomerase (GPI)/neuroleukin (NLK) mRNA. This surprising homology was confirmed in Western blots demonstrating that mAb A36 reacted specifically with GPI obtained from rabbit muscle and from baker's yeast. Moreover, polyclonal, monospecific antibodies produced against beta-galactosidase/SA-36-3 fusion protein stained human spermatozoa and caused intensive agglutination of these cells in a manner similar to that with the mAb. Taken together, the data presented here demonstrated that mAb A36 cognate sperm surface antigen, encoded by SA-36 cDNA, is a GPI/NLK-like protein involved in sperm agglutination.

The crystal structure of rabbit phosphoglucose isomerase complexed with 5-phospho- d -arabinonohydroxamic acid

“…These proteins promote antibody secretion by mononuclear cells, tumor cell motility, and differentiation of leukemia cells and a promyelocytic cell line (HL-60 cells), respectively. More recently, PGI has also been identified as the antigen involved in rheumatoid arthritis of a mouse line (13), as a specific inhibitor toward myofibril-bound serine proteinase (14), and as the surface antigen involved in sperm agglutination (15). Because very little is known about how PGI is precisely involved in these various biological processes, this moonlighting protein (16) has been the subject of intense investigations.…”

Identification of differentially expressed genes in the developmental stages from olive flounderParalichthys olivaceususing an annealing control primer system

“…PGI acts as a potent mitogen/cytokine (i.e., tumor autocrine mobility factor, neuroleukin, and maturation factor; Chaput et al 1988;Watanabe et al 1996;Xu et al 1996) and therefore represents a unique example of a 'moonlighting protein' which exhibits multiple cellular functions (Jeffery 1999). Other previously unknown factors and functions, such as a sperm antigen involved in sperm agglutination from mouse sperm and a novel serine proteinase inhibitor from the skeletal muscle of white croaker, Argyrosomus argentatus, were also reported recently (Cao et al 2000;Yakirevich and Naot 2000). The deduced amino acid sequence of flounder PGI was compared with PGI sequences from other species.…”

Existence of Unprocessed a Mitochondrial Enzyme: YDL178wp in the Membrane Fraction as an Oligomeric Formation with a Protein-Unfolding Activity

“…In fact, a lot of proteins possessing the characterization of protein moonlighting have been identified so far; e.g. glucose-6-phosphate isomerase as neuroleukin [22][23][24][25], the cytokine secreted from T cells as metaroprotease 1 [26], oncogene nm23 as nucleoside-triphosphate (NDP) kinase [27] lens crystalline as lactate dehydrogenase (LDH) [28]. Furthermore, recently, a lot of alternative transport/secretion pathways have found out as the unconventional pathway [29][30][31], and thus the dogma of protein transport have been changing.…”