Tissue distribution and subcellular localization of phosphatidylcholine transfer protein in rats as determined by radioimmunoassay.
A radioimmunoassay for the phosphatidylcholine-transfer protein from rat liver was used to measure levels of PC-transfer protein in rat tissues. The assay as described before (Teerlink, T., Poorthuis, B.J.H.M., Van der Krift, T.P. and Wirtz, K.W.A., Biochim. Biophys. Acta 665 (1981) 74-80) was modified in order to measure PC-transfer protein in tissue homogenates and subcellular membrane fractions. To this end both a detergent (Triton X-100) and a proteolytic enzyme inhibitor (aprotinin) were added to the assay medium. The radioimmunoassay measured levels of PC-transfer protein in the range of 5-50 ng and was specific for PC-transfer protein from rat tissues. Subcellular distribution studies showed that in 10% (w/v) homogenates of liver approximately 60% of the PC-transfer protein was present in the 105000 X g supernatant fraction, the remainder being evenly distributed over the particulate fractions. PC-transfer protein associated with the particulate fractions was almost completely removed by a single washing step, suggesting a dynamic equilibrium between membrane-bound and soluble PC-transfer protein. Both 105000 X g supernatants and homogenates of various rat tissues were assayed. The highest levels of PC-transfer protein were measured in liver and intestinal mucosa. Lower values were found in kidney, spleen and lung, whereas heart and brain contained hardly any PC-transfer protein. PC-transfer protein levels in regenerating rat liver did not differ significantly from levels in normal liver. In fetal lung a change in PC-transfer protein content during development was observed, with a clear maximum 2 days before term, suggesting an involvement of PC-transfer protein in the secretion of lung surfactant.
D000375:Aging; D000727:Androgen-Binding Protein; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D049294:Phospholipid Transfer Proteins; D060789:Prostatein; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D011919:Rats, Inbred Strains; D060765:Secretoglobins; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution; D014598:Uteroglobin; D060788:Mammaglobin B
D000727:Androgen-Binding Protein; D002352:Carrier Proteins; D049294:Phospholipid Transfer Proteins; D060789:Prostatein; D060765:Secretoglobins; D014598:Uteroglobin; C511484:Scgb1d2 protein, rat; C511483:Scgb1d4 protein, rat; C556468:Scgb2a1 protein, rat; D060788:Mammaglobin B