Harper K D, McLeod J F, Kowalski M A, Haddad J G
J Clin Invest. 1987 May;79(5):1365-70. doi: 10.1172/JCI112963.
Plasma vitamin D binding protein (DBP) may scavenge actin released during cell lysis. We examined the plasma disappearance and tissue appearance of 125I-DBP, 125I-G-actin, and the DBP-G-actin complex after their intravenous administration to rats. The plasma disappearance of DBP and DBP-actin were indistinguishable, with rapid initial (t1/2 = 2.6 h) and slower second (t1/2 = 7 h) slopes. After 125I-G-actin (nanomole) injection, plasma disappearance paralleled that of DBP and DBP-actin. All injected actin was associated with DBP, without evidence of free actin, actin-gelsolin complexes or actin oligomers. Tissue appearances of 125I-apo-DBP (apo) or holo-DBP were similar, with highest accumulations in perfused liver, kidney, and skeletal muscle. Although more complex phenomena (plasma entry of F-actin and intracellular actin binding proteins) would occur in vivo after cell lysis, our results suggest a role for DBP in the sequestration and disposition of actin monomers in the circulation.
血浆维生素D结合蛋白(DBP)可能会清除细胞裂解过程中释放的肌动蛋白。我们在给大鼠静脉注射125I-DBP、125I-G-肌动蛋白和DBP-G-肌动蛋白复合物后,检测了它们在血浆中的消失情况以及在组织中的出现情况。DBP和DBP-肌动蛋白在血浆中的消失情况无法区分,最初快速(半衰期 = 2.6小时),随后较慢(半衰期 = 7小时)。注射125I-G-肌动蛋白(纳摩尔)后,血浆消失情况与DBP和DBP-肌动蛋白相似。所有注射的肌动蛋白都与DBP结合,没有游离肌动蛋白、肌动蛋白-凝溶胶蛋白复合物或肌动蛋白寡聚体的证据。125I-脱辅基DBP(脱辅基)或全DBP在组织中的出现情况相似,在灌注的肝脏、肾脏和骨骼肌中积累最多。尽管细胞裂解后体内会出现更复杂的现象(F-肌动蛋白进入血浆和细胞内肌动蛋白结合蛋白),但我们的结果表明DBP在循环中隔离和处置肌动蛋白单体方面发挥了作用。