Lm. Matovcik et al., DARPP-32 (DOPAMINE AND CAMP-REGULATED PHOSPHOPROTEIN, M(R)-32,000) ISA MEMBRANE-PROTEIN IN THE BOVINE PARATHYROID, FEBS letters, 364(1), 1995, pp. 67-74
A distinct form of DARPP-32, a protein phosphatase-1 inhibitor, has be
en identified in bovine calf parathyroid glands. Immunoblot analysis o
f parathyroid tissue revealed a 32 kDa protein present predominantly i
n a particulate fraction; it remained particulate after treatment with
1.0 M NaCl or 0.1 M Na2CO3. Metabolic labeling of parathyroid cells w
ith mevalonolactone demonstrated that DARPP-32 is isoprenylated. Immun
ocytochemical localization studies demonstrated that DARPP-32 is prese
nt in vesicles throughout the cytoplasm of parathyroid cells, and that
protein phosphatase-ly is concentrated in the region of the plasma me
mbrane. Thus, in contrast to the predominately soluble form of DARPP-3
2 that has been characterized in selected areas of the central nervous
system, the parathyroid form is tightly associated with intracellular
membranes.