Ratcliffe W A, Green E, Emly J, Norbury S, Lindsay M, Heath D A, Ratcliffe J G
Wolfson Research Laboratories, Department of Clinical Chemistry, Queen Elizabeth Medical Centre, Edgbaston, Birmingham.
J Endocrinol. 1990 Oct;127(1):167-76. doi: 10.1677/joe.0.1270167.
Parathyroid hormone-related protein (PTHrP) was measured in human and bovine milk by radioimmunoassay (RIA) and bioassay, and the molecular forms characterized by gel chromatography and immunoblotting of affinity-purified PTHrP. Mean immunoreactive PTHrP(1-34) concentrations were 23 and 87 micrograms/l in human and bovine milk respectively. Bioactive (BIO) PTHrP concentrations determined by cyclic AMP production by ROS 17/2.8 cells correlated significantly (P less than 0.001) with those obtained by RIA (BIO = 1.04RIA--3.4, r = 0.939). Gel filtration of human and bovine milk identified several peaks with immunoactivity and bioactivity. Immunoblotting of affinity-purified PTHrP revealed multiple molecular species including components with mobilities similar to those of PTHrP and its subfragments. These studies confirm the presence of immuno- and bioactive PTHrP in milk and suggest that post-translational processing is complex and variable.
采用放射免疫分析法（RIA）和生物测定法对人乳和牛乳中的甲状旁腺激素相关蛋白（PTHrP）进行了测定，并通过凝胶色谱法和亲和纯化的PTHrP免疫印迹法对其分子形式进行了表征。人乳和牛乳中免疫反应性PTHrP(1-34)的平均浓度分别为23微克/升和87微克/升。通过ROS 17/2.8细胞产生环磷酸腺苷所测定的生物活性（BIO）PTHrP浓度与通过RIA获得的浓度显著相关（P<0.001）（BIO = 1.04RIA - 3.4，r = 0.939）。对人乳和牛乳进行凝胶过滤，鉴定出了几个具有免疫活性和生物活性的峰。亲和纯化的PTHrP免疫印迹显示出多种分子形式，包括迁移率与PTHrP及其亚片段相似的成分。这些研究证实了乳汁中存在免疫活性和生物活性的PTHrP，并表明翻译后加工过程复杂且多变。
