9IKP | pdb_00009ikp

Crystal structure of human malectin

  • Classification: SUGAR BINDING PROTEIN
  • Organism(s): Homo sapiens
  • Expression System: Escherichia
  • Mutation(s): No 

  • Deposited: 2024-06-28 Released: 2025-07-02 
  • Deposition Author(s): Si, Y.L.
  • Funding Organization(s): National Natural Science Foundation of China (NSFC)

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.68 Å
  • R-Value Free: 
    0.211 (Depositor), 0.206 (DCC) 
  • R-Value Work: 
    0.172 (Depositor), 0.169 (DCC) 
  • R-Value Observed: 
    0.173 (Depositor) 

Starting Model: experimental
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wwPDB Validation 3D Report Full Report

Validation slider image for 9IKP

Ligand Structure Quality Assessment 


This is version 1.1 of the entry. See complete history

Literature

Malectin Alleviates Endoplasmic Reticulum Stress in Gestational Diabetes Mellitus via Glycoprotein Quality Control Mechanisms.

Zhu, J.Zhang, Y.Wang, Y.Zhu, X.Yuan, A.Yin, W.Yu, H.Pang, X.He, Y.Wang, Y.Wang, T.Li, Y.Si, Y.

(2026) Adv Sci (Weinh) : e08901-e08901

  • DOI: https://doi.org/10.1002/advs.202508901
  • Primary Citation Related Structures: 
    9IKP, 9IL3, 9ILA, 9ILF

  • PubMed Abstract: 

    Gestational diabetes mellitus (GDM), is a prevalent metabolic disorder associated with placental dysfunction and adverse pregnancy outcomes. Emerging evidence points to endoplasmic reticulum (ER) stress as a potential initiating factor in GDM pathogenesis. Moreover, ER stress-mediated trophoblast dysfunction is recognized as a critical pathological mechanism, yet its precise role remains incompletely elucidated. Here, we demonstrate that malectin, an ER-resident lectin, is upregulated in GDM placentas and protects trophoblasts against high glucose (HG)-induced ER stress. Mechanistically, malectin recognizes Glc2-N-glycans on misfolded glycoproteins via six essential carbohydrate-binding residues, thereby facilitating glycoprotein quality control (GQC). Malectin knockdown exacerbated HG-induced ER stress, apoptosis, and impaired trophoblast invasion, syncytialization, and glucose uptake, whereas its overexpression attenuated these defects. Structural analyses revealed the molecular basis for malectin's specificity toward Glc2-N-glycan motifs. Importantly, administration of TAT-Malectin ameliorated hyperglycemia and placental ER stress in a GDM mouse model. In summary, our study provides the first evidence that malectin protects placental trophoblasts from HG-induced ER stress and damage through GQC mediated by its six key carbohydrate-binding residues. These findings establish malectin as both a key endogenous placental protector and a promising protein therapeutic candidate, offering a novel target and therapeutic strategy for GDM.


  • Organizational Affiliation
    • Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China.

Macromolecule Content 

  • Total Structure Weight: 41.87 kDa 
  • Atom Count: 3,433 
  • Modeled Residue Count: 368 
  • Deposited Residue Count: 368 
  • Unique protein chains: 1

Macromolecules

Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
Malectin
A, B
184Homo sapiensMutation(s): 0 
Gene Names: MLECKIAA0152
UniProt & NIH Common Fund Data Resources
Find proteins for Q14165 (Homo sapiens)
Explore Q14165 
Go to UniProtKB:  Q14165
PHAROS:  Q14165
GTEx:  ENSG00000110917 
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ14165
Sequence Annotations
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Reference Sequence

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.68 Å
  • R-Value Free:  0.211 (Depositor), 0.206 (DCC) 
  • R-Value Work:  0.172 (Depositor), 0.169 (DCC) 
  • R-Value Observed: 0.173 (Depositor) 
Space Group: P 31
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 100.656α = 90
b = 100.656β = 90
c = 36.188γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
autoPXdata processing
autoPXdata reduction
PHENIXphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

& Funding Information

Deposition Data

  • Released Date: 2025-07-02 
  • Deposition Author(s): Si, Y.L.

Funding OrganizationLocationGrant Number
National Natural Science Foundation of China (NSFC)China82201916

Revision History  (Full details and data files)

  • Version 1.0: 2025-07-02
    Type: Initial release
  • Version 1.1: 2026-07-15
    Changes: Database references