Expression and compartmentalisation of the glycolytic enzymes GAPDH and pyruvate kinase in boar spermatogenesis

Abstract

Boar spermatozoa contain isoforms of both glyceraldehyde 3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) and pyruvate kinase (PK, EC 2.7.1.40). The sperm-specific forms, GAPDH-S and PK-S, are tightly bound to cell structures. By immunofluorescence microscopy GAPDH-S and PK-S were localised in the principal piece of the boar sperm flagellum as well as in the acrosomal region of the sperm head and at the head-midpiece junction. The midpiece of the flagellum, however, contains isoforms of GAPDH and PK that were only recognised by antibodies against somatic GAPDH and PK, respectively, but not by the antibodies against GAPDH-S and PK-S. In sections of boar testis, GAPDH-S and PK-S were first detected in elongating spermatids when both the developing flagellum and the head were labelled with antibodies against GAPDH-S and PK-S. In contrast, antibodies against rabbit muscle GAPDH and PK labelled all developmental stages of germ cells and also neighbouring contractile cells. Thus, the structure-bound sperm-specific enzymes, GAPDH-S and PK-S, appeared only late in spermatogenesis simultaneously with the development of the structures to which they are bound. Anchoring glycolytic enzymes to structures in these mitochondria-free regions may secure ATP-production for both motility and acrosome function.

Bovine sperm plasma membrane proteomics through biotinylation and subcellular enrichment

“…Surprisingly, some of them, aldolase A (ALDOA) and triosephosphate isomerase (TPI1), have been proposed to mediate interactions with ZP glycoproteins . Our data also affirmed the presence of metabolic enzymes such as hexokinase‐1 (HK1) , glyceraldehydes‐3‐phosphate dehydrogenase (GAPDHS) pyruvate kinase (PK) , and enolase‐1 (ENO1) . These proteins have been found in posterior and anterior regions of the sperm head in murines and boar, ENO1 in human sperm.…”

Comparative Proteome Analysis of Cryopreserved Flagella and Head Plasma Membrane Proteins from Sea Bream Spermatozoa: Effect of Antifreeze Proteins

“…Spot 10Fl was identified as Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). This protein is expressed in sperm at specific stages of spermiogenesis and can still be detected in mature spermatozoa of vertebrates [43]. Variations in the expression of GAPDH block the progressive motility of spermatozoa [44].…”

Glucose is a pH-Dependent Motor for Sperm Beat Frequency during Early Activation

“…For the rabbit muscle, it was demonstrated that this enzyme dissociates into inactive subunits under acidic conditions and re-associates into the active form when the pH is raised again [6], [7], [36]. In quiescent epididymal mouse spermatozoa hexokinase activity was significantly lower compared to that of sperm incubated in physiological buffer [36].…”

“…Besides mitochondrial respiration, glycolysis is a major pathway for ATP production in murine spermatozoa [2], [3], [4]. Glycolytic enzymes are located in the fibrous sheath of the sperm tail [5] and some of them exhibit sperm-specific properties, such as type1 hexokinase (HK1S) [6], pyruvate kinase (PKS) [7] and glyceraldehyde 3-phosphate dehydrogenase (GAPDS) [8]. The fibrous sheath covers the outer dense fibers which, in turn, are located in close proximity to the microtubules.…”