Identification and partial characterization of parathyroid hormone-related protein in human and bovine milk.
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.
Ratcliffe
W A
WA
Wolfson Research Laboratories, Department of Clinical Chemistry, Queen Elizabeth Medical Centre, Edgbaston, Birmingham.
Green
E
E
Emly
J
J
Norbury
S
S
Lindsay
M
M
Heath
D A
DA
Ratcliffe
J G
JG
D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D008892:Milk / Q000737:chemistry*; D009363:Neoplasm Proteins / Q000032:analysis* / Q000737:chemistry; D012516:Osteosarcoma / Q000737:chemistry; D010281:Parathyroid Hormone / Q000032:analysis* / Q000737:chemistry; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D011863:Radioimmunoassay
D009363:Neoplasm Proteins; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; C054296:parathyroid hormone-related protein (1-34); C025076:parathyroid hormone (1-34), bovine