Extraction, purification, and partial characterization of bovine parathyroid secretory protein.

K Takatsuki,A.B Schneider,K.Y Shin,L.M Sherwood

doi:10.1016/s0021-9258(19)69785-1

Abstract

Parathyroid secretory protein (PSP) was purified from extracts of bovine parathyroid glands using radioactive PSP as a marker during purification. The labeled preparation was obtained by gel filtration of medium resulting from incubation of parathyroid glands with radioactive amino acids for 4 h. Alkaline extraction, ammonium sulfate precipitation, ion-exchange chromatography on DEAE-cellulose, and gel filtration over Bio-Gel A 1.5 M and A 5 M resulted in a homogeneous product. Purified PSP monomer had a Mr = 67,000, was highly acidic on gel electrophoresis, and contained over 35% glutamic and aspartic acid residues. Approximately 18% of the protein consisted of carbohydrate residues. The homogeneity of the final product was established by polyacrylamide and sodium dodecyl sulfate (SDS) gel electrophoresis and the identification of a single NH2-terminal leucine. A radioimmunoassay for PSP was developed to identify the protein in tissue extracts and in incubation medium. Purification of PSP should be useful in defining further its biochemistry, biologic function, and control of secretion.

Highlights

Inthepresentstudy, we have described a method for extracting and purifying Parathyroid secretory protein (PSP), an M, = 67,000 protein which is released from the parathyroidglands in parallel withPTH
Recent studies have suggested that PSP is located in the secretory granules of the parathyroid cell [6], that itis synthesized as a presecretory proteinlike other proteins that are destined for extracellular release [19], and that it shares an intracellular distribution similar to that of PTH and its precursor proteins [22]
On sodium dodecyl sulfate (SDS)-gel electrophoresis without parathyroid hormone is the most important pro- boiling, PSP migrated in the same position as albumin. tein secreted by the parathyroid gland, it has been shown in Earlier studiesby Kemper et al [1]suggested that PSP might in vitro studies using radioactive amino acids that proteinsof be a dimer on gel filtration, and this has been confmed in higher molecular weight are released [1,2,3,4]

Summary

Introduction

Purified PSP monomer had a M, = 67,000, was highly acidic on gel electrophoresis, and contained over 35% glutamic and aspartic acid residues. Inthepresentstudy, we have described a method for extracting and purifying PSP, an M , = 67,000 protein which is released from the parathyroidglands in parallel withPTH.

Results

Conclusion