The basis of echinocytosis of the erythrocyte by glucose depletion.
Echinocytosis of erythrocytes by glucose depletion is attributed to adenosine triphosphate depletion, but its process still remains unknown. A mechanism of control of the erythrocyte shape has been previously proposed in which the anion exchanger Band 3, linked to flexible membrane skeleton, has a pivotal role. Recruitments of its inward facing (Band 3(i) ) and outward facing (Band 3(o) ) conformations contract and relax the membrane skeleton, thus promoting echinocytosis and stomatocytosis, respectively. The Band 3(o) /Band 3(i) equilibrium ratio increases with the increase of the Donnan equilibrium ratio, and preferential inward and outward transport by Band 3 of substrates slowly transported are echinocytogenic and stomatocytogenic, respectively. The mechanism suggests the following process. The major organic phosphate 2,3-bisphosphoglycerate is catabolized to lactate to form inorganic phosphate, 3-phosphoglycerate, and adenosine triphosphate. The last two products can be reversibly transformed into 1,3-bisphosphoglycerate and adenosine diphosphate by the glycolytic enzyme phosphoglycerate kinase, thus allowing 2,3-bisphosphoglycerate formation by 2,3-bisphosphoglycerate synthase/phosphatase. The catabolic and cyclic processes initially oppose echinocytosis by increasing the Donnan ratio and outward transport of slowly transported inorganic phosphate by Band 3 (its basic form is transported with a hydrogen ion). Echinocytosis occurs when inward transport of this product becomes predominant. This process can rationalize direct and indirect observations.
Laboratoire de Chimie des Protéines, Montréal, Québec, Canada. pwong_LCP@yahoo.ca
Pierre
P
Wong
D000255:Adenosine Triphosphate / Q000378:metabolism; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D048430:Cell Shape; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans
D001457:Anion Exchange Protein 1, Erythrocyte; D000255:Adenosine Triphosphate; D005947:Glucose