To date, many GH74 family xyloglucanases have been identified and divided into three modes of activity: exo, endo-dissociative, and endo-processive. Recently, crystal structure analysis and homology modeling have determined the key structures and amino acid residues for exo and endo-processive GH74 xyloglucanase activities. For example, Geotrichum OXG-RCBH, an exo mode enzyme, has an exo-loop that blocks one side of the active site cleft and is essential for exo-mode activity. In addition, Paenibacillus XEG74, an endo-processive mode enzyme, has characteristic tryptophan residues at positive subsites of the active site cleft. These tryptophan residues are vital for endo-processive-type activity, and mutation in these tryptophan residues results in a change from endo-processive to endo-dissociative activity. In this review, we focus on the structures and modes of activity of GH74 family xyloglucanases.

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Galectins, β-galactoside binding lectins, are involved in various physiological and pathological events. The corpus luteum (CL) is a transient endocrine tissue that produces large amounts of progesterone, which is essential for a successful pregnancy, and stage-specifically expresses galectin-1 and galectin-3. We herein summarized current knowledge on galectins in the CL of mice, cows, and women in order to clarify the expression profiles, regulatory mechanisms, and possible roles of galectins in the CL of different species. The regressing CL of mice contained both galectin-1 and galectin-3, suggesting an involvement of galectins in the regulation of luteolysis in mice. On the other hand, the healthy functional CL of cows and women abundantly expressed galectin-1, whereas galectin-3 was increased in the regressing CL. The expression of galectin in luteal cells is differentially regulated by known endocrine and paracrine molecules such as prolactin, luteinizing hormone, human chorionic gonadotropin, and prostaglandins E and F. Interestingly, α2,6-sialylation, which inhibit galectin-1 binding and are catalyzed by ST6GAL1, were increased in the regressing CL of all animals. These findings suggest that a “galectin switch”, coordinated changes in glycans and galectins in association with luteal function, represents a conserved mechanism in the regulation of luteal function beyond species.

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To date, many GH74 family xyloglucanases have been identified and divided into three modes of activity: exo, endo-dissociative, and endo-processive. Recently, crystal structure analysis and homology modeling have determined the key structures and amino acid residues for exo and endo-processive GH74 xyloglucanase activities. For example, Geotrichum OXG-RCBH, an exo mode enzyme, has an exo-loop that blocks one side of the active site cleft and is essential for exo-mode activity. In addition, Paenibacillus XEG74, an endo-processive mode enzyme, has characteristic tryptophan residues at positive subsites of the active site cleft. These tryptophan residues are vital for endo-processive-type activity, and mutation in these tryptophan residues results in a change from endo-processive to endo-dissociative activity. In this review, we focus on the structures and modes of activity of GH74 family xyloglucanases.

View full abstract

Galectins, β-galactoside binding lectins, are involved in various physiological and pathological events. The corpus luteum (CL) is a transient endocrine tissue that produces large amounts of progesterone, which is essential for a successful pregnancy, and stage-specifically expresses galectin-1 and galectin-3. We herein summarized current knowledge on galectins in the CL of mice, cows, and women in order to clarify the expression profiles, regulatory mechanisms, and possible roles of galectins in the CL of different species. The regressing CL of mice contained both galectin-1 and galectin-3, suggesting an involvement of galectins in the regulation of luteolysis in mice. On the other hand, the healthy functional CL of cows and women abundantly expressed galectin-1, whereas galectin-3 was increased in the regressing CL. The expression of galectin in luteal cells is differentially regulated by known endocrine and paracrine molecules such as prolactin, luteinizing hormone, human chorionic gonadotropin, and prostaglandins E and F. Interestingly, α2,6-sialylation, which inhibit galectin-1 binding and are catalyzed by ST6GAL1, were increased in the regressing CL of all animals. These findings suggest that a “galectin switch”, coordinated changes in glycans and galectins in association with luteal function, represents a conserved mechanism in the regulation of luteal function beyond species.

View full abstract