Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review
A Complex Dance : The Importance of Glycosaminoglycans and Zinc in the Aggregation of Human Prolactin. / Christensen, Line Friis Bakmann; Malmos, Kirsten Gade; Christiansen, Gunna et al.
In: Biochemistry, Vol. 55, No. 26, 22.06.2016, p. 3674–3684.Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review
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TY - JOUR
T1 - A Complex Dance
T2 - The Importance of Glycosaminoglycans and Zinc in the Aggregation of Human Prolactin
AU - Christensen, Line Friis Bakmann
AU - Malmos, Kirsten Gade
AU - Christiansen, Gunna
AU - Otzen, Daniel Erik
PY - 2016/6/22
Y1 - 2016/6/22
N2 - The zinc binding hormone pituitary human prolactin (hPRL) is stored in secretory granules of specialized cells in an aggregated form. Glycosaminoglycans (GAGs) are anionic polysaccharides commonly associated with secretory granules, indicating their involvement in granule formation. Here we, for the first time, study the impact of GAGs in combination with Zn(2+) on the reversible hPRL aggregation across the pH range of 7.4-5.5. Zn(2+) alone causes hPRL aggregation at pH 7.4, while aggregation between pH 7.4 and 5.5 requires both Zn(2+) and GAGs. GAGs alone cause hPRL aggregation below pH 5.5. Comprehensive thermal stability investigations show that hPRL is particularly destabilized toward thermal denaturation at pH 5.5 and that GAGs increasingly destabilize hPRL at decreasing pH values. We propose that Zn(2+) causes hPRL aggregation through low-affinity Zn(2+) binding sites on hPRL with GAGs facilitating Zn(2+) binding by neutralizing repulsive positive charges of hPRL in the acidic environments of the TGN and mature secretory granules. In a manner independent of the aggregation-causing agent(s), the different hPRL aggregates show very similar secondary structure and amorphous morphology. We speculate that this may be a recognizable sorting signal in the formation of hPRL granular vesicles.
AB - The zinc binding hormone pituitary human prolactin (hPRL) is stored in secretory granules of specialized cells in an aggregated form. Glycosaminoglycans (GAGs) are anionic polysaccharides commonly associated with secretory granules, indicating their involvement in granule formation. Here we, for the first time, study the impact of GAGs in combination with Zn(2+) on the reversible hPRL aggregation across the pH range of 7.4-5.5. Zn(2+) alone causes hPRL aggregation at pH 7.4, while aggregation between pH 7.4 and 5.5 requires both Zn(2+) and GAGs. GAGs alone cause hPRL aggregation below pH 5.5. Comprehensive thermal stability investigations show that hPRL is particularly destabilized toward thermal denaturation at pH 5.5 and that GAGs increasingly destabilize hPRL at decreasing pH values. We propose that Zn(2+) causes hPRL aggregation through low-affinity Zn(2+) binding sites on hPRL with GAGs facilitating Zn(2+) binding by neutralizing repulsive positive charges of hPRL in the acidic environments of the TGN and mature secretory granules. In a manner independent of the aggregation-causing agent(s), the different hPRL aggregates show very similar secondary structure and amorphous morphology. We speculate that this may be a recognizable sorting signal in the formation of hPRL granular vesicles.
U2 - 10.1021/acs.biochem.6b00153
DO - 10.1021/acs.biochem.6b00153
M3 - Journal article
C2 - 27305175
VL - 55
SP - 3674
EP - 3684
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 26
ER -