Biomolecules 2014, 4(2), 474-497; doi:10.3390/biom4020474
Review

The Role of Histidine-Proline-Rich Glycoprotein as Zinc Chaperone for Skeletal Muscle AMP Deaminase

1email, 2email and 1,* email
Received: 6 February 2014; in revised form: 8 April 2014 / Accepted: 10 April 2014 / Published: 5 May 2014
(This article belongs to the Special Issue Metal Binding Proteins)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Metallochaperones function as intracellular shuttles for metal ions. At present, no evidence for the existence of any eukaryotic zinc-chaperone has been provided although metallochaperones could be critical for the physiological functions of Zn2+ metalloenzymes. We propose that the complex formed in skeletal muscle by the Zn2+ metalloenzyme AMP deaminase (AMPD) and the metal binding protein histidine-proline-rich glycoprotein (HPRG) acts in this manner. HPRG is a major plasma protein. Recent investigations have reported that skeletal muscle cells do not synthesize HPRG but instead actively internalize plasma HPRG. X-ray absorption spectroscopy (XAS) performed on fresh preparations of rabbit skeletal muscle AMPD provided evidence for a dinuclear zinc site in the enzyme compatible with a (μ-aqua)(μ-carboxylato)dizinc(II) core with two histidine residues at each metal site. XAS on HPRG isolated from the AMPD complex showed that zinc is bound to the protein in a dinuclear cluster where each Zn2+ ion is coordinated by three histidine and one heavier ligand, likely sulfur from cysteine. We describe the existence in mammalian HPRG of a specific zinc binding site distinct from the His-Pro-rich region. The participation of HPRG in the assembly and maintenance of skeletal muscle AMPD by acting as a zinc chaperone is also demonstrated.
Keywords: AMP deaminase; histidine-proline-rich glycoprotein; zinc chaperone; zinc binding site
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MDPI and ACS Style

Ranieri-Raggi, M.; Moir, A.J.G.; Raggi, A. The Role of Histidine-Proline-Rich Glycoprotein as Zinc Chaperone for Skeletal Muscle AMP Deaminase. Biomolecules 2014, 4, 474-497.

AMA Style

Ranieri-Raggi M, Moir AJG, Raggi A. The Role of Histidine-Proline-Rich Glycoprotein as Zinc Chaperone for Skeletal Muscle AMP Deaminase. Biomolecules. 2014; 4(2):474-497.

Chicago/Turabian Style

Ranieri-Raggi, Maria; Moir, Arthur J.G.; Raggi, Antonio. 2014. "The Role of Histidine-Proline-Rich Glycoprotein as Zinc Chaperone for Skeletal Muscle AMP Deaminase." Biomolecules 4, no. 2: 474-497.

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