title: The crystal structure of human protein α1M reveals a chromophore-binding site and two putative protein-protein interfaces.
abstract: Lipocalin α1-microglobulin (α1M) is a conserved glycoprotein present in plasma and in the interstitial fluids of all tissues. α1M is linked to a heterogeneous yellow-brown chromophore of unknown structure, and interacts with several target proteins, including α1-inhibitor-3, fibronectin, prothrombin and albumin. To date, there is little knowledge about the interaction sites between α1M and its partners. Here, we report the crystal structure of the human α1M. Due to the crystallization occurring in a low ionic strength solution, the unidentified chromophore with heavy electron density is observed at a hydrophobic inner tube of α1M. In addition, two conserved surface regions of α1M are proposed as putative protein-protein interface sites. Further study is needed to unravel the detailed information about the interaction between α1M and its partners.
authors.affiliation: Key Laboratory of Molecular Biology on Infectious Disease, Chongqing Medical University, YiXueYuanlu-1, Chongqing 400016, China; College of Laboratory Medicine, Chongqing Medical University, YiXueYuanlu-1, Chongqing 400016, China; The Center for Clinical Molecular Medical detection of Chongqing, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
authors.forename: Yangli
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zengqiang
authors.initials: Z
authors.lastname: Gao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Guo
authors.forename: Hongpeng
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Miao
authors.initials: M
authors.lastname: Luo
authors.forename: Haifeng
authors.initials: H
authors.lastname: Hou
authors.forename: Ailong
authors.initials: A
authors.lastname: Huang
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Dong
authors.forename: Deqiang
authors.initials: D
authors.lastname: Wang
mesh_terms: D000510:Alpha-Globulins / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D016415:Sequence Alignment
chemical_list: D000510:Alpha-Globulins; C016001:alpha-1-microglobulin
keywords: Chromophore; Crystal structure; Homodimer; Interface; α1-Microglobulin