Multiple growth hormone-binding proteins are expressed on insulin-producing cells
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Multiple growth hormone-binding proteins are expressed on insulin-producing cells. / Møldrup, A; Billestrup, N; Thorn, N A; Lernmark, A; Nielsen, Jens Høiriis.
In: Molecular endocrinology (Baltimore, Md.), Vol. 3, No. 8, 08.1989, p. 1173-82.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Multiple growth hormone-binding proteins are expressed on insulin-producing cells
AU - Møldrup, A
AU - Billestrup, N
AU - Thorn, N A
AU - Lernmark, A
AU - Nielsen, Jens Høiriis
PY - 1989/8
Y1 - 1989/8
N2 - The insulin-producing rat islet tumor cell line, RIN-5AH, expresses somatogen binding sites and responds to GH by increased proliferation and insulin production. Affinity cross-linking shows that RIN-5AH cells contain two major GH-binding subunits of Mr 100-130K (110K), which appear to exist as disulfide-linked multimers of Mr 270-350K (300K). In addition, a minor Mr 180K GH-binding protein is identified which does not appear to be associated with other proteins by disulfide bridges. A plasma membrane-enriched fraction accounts for 86% of the RIN-cell GH-binding activity while cytosol and intracellular organelles are low in GH-binding activity. The plasma membrane-bound activity is soluble in Triton X-100 with intact hormone binding characteristics. The apparent KD in detergent solution is estimated to 18 ng/ml (8 x 10(-10) M). 125I-hGH-affinity cross-linking to intact and detergent-solubilized membranes as well as hGH-affinity purified protein reveals labeled proteins of Mr 180K and Mr 285-350K. In contrast to the cross-linked Mr 300K complexes of intact cells those of disintegrated cellular material are resistant to reduction with dithiothreitol, and it is speculated that this is due to intersubunit cross-linking of the disulfide-linked Mr 110K GH-binding subunits. The GH-binding proteins are purified approximately 100-fold by one cycle of hGH-affinity chromatography and five major proteins of Mr 180K, 94K, 86K, 64K, and 54K are identified by silver staining in the purified fraction. It is concluded that the RIN-5AH cells have multiple GH-binding proteins which may mediate signals for either proliferation and/or insulin production.
AB - The insulin-producing rat islet tumor cell line, RIN-5AH, expresses somatogen binding sites and responds to GH by increased proliferation and insulin production. Affinity cross-linking shows that RIN-5AH cells contain two major GH-binding subunits of Mr 100-130K (110K), which appear to exist as disulfide-linked multimers of Mr 270-350K (300K). In addition, a minor Mr 180K GH-binding protein is identified which does not appear to be associated with other proteins by disulfide bridges. A plasma membrane-enriched fraction accounts for 86% of the RIN-cell GH-binding activity while cytosol and intracellular organelles are low in GH-binding activity. The plasma membrane-bound activity is soluble in Triton X-100 with intact hormone binding characteristics. The apparent KD in detergent solution is estimated to 18 ng/ml (8 x 10(-10) M). 125I-hGH-affinity cross-linking to intact and detergent-solubilized membranes as well as hGH-affinity purified protein reveals labeled proteins of Mr 180K and Mr 285-350K. In contrast to the cross-linked Mr 300K complexes of intact cells those of disintegrated cellular material are resistant to reduction with dithiothreitol, and it is speculated that this is due to intersubunit cross-linking of the disulfide-linked Mr 110K GH-binding subunits. The GH-binding proteins are purified approximately 100-fold by one cycle of hGH-affinity chromatography and five major proteins of Mr 180K, 94K, 86K, 64K, and 54K are identified by silver staining in the purified fraction. It is concluded that the RIN-5AH cells have multiple GH-binding proteins which may mediate signals for either proliferation and/or insulin production.
KW - Affinity Labels
KW - Animals
KW - Cell Fractionation
KW - Cell Line
KW - Cell Membrane
KW - Chromatography, Affinity
KW - Cross-Linking Reagents
KW - Islets of Langerhans
KW - Octoxynol
KW - Polyethylene Glycols
KW - Rats
KW - Receptors, Somatotropin
KW - Succinimides
M3 - Journal article
C2 - 2674691
VL - 3
SP - 1173
EP - 1182
JO - Molecular Endocrinology
JF - Molecular Endocrinology
SN - 0888-8809
IS - 8
ER -
ID: 47974246