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Spastic paraplegia 21 (autosomal recessive, Mast syndrome)
Symbols SPG21 ; ACP33; BM-019; GL010; MAST
External IDs OMIM608181 MGI106403 HomoloGene9603 GeneCards: SPG21 Gene
RNA expression pattern
PBB GE SPG21 217827 s at tn.png
More reference expression data
Species Human Mouse
Entrez 51324 27965
Ensembl ENSG00000090487 ENSMUSG00000032388
UniProt Q9NZD8 Q9CQC8
RefSeq (mRNA) NM_001127889 NM_138584
RefSeq (protein) NP_001121361 NP_613050
Location (UCSC) Chr 15:
64.96 – 64.99 Mb
Chr 9:
65.46 – 65.49 Mb
PubMed search [1] [2]

Maspardin is a protein that in humans is encoded by the SPG21 gene.[1][2][3]

The protein encoded by this gene was identified by a two-hybrid screen using CD4 as the bait. It binds to the hydrophobic C-terminal amino acids of CD4 which are involved in repression of T cell activation. The interaction with CD4 is mediated by the noncatalytic alpha/beta hydrolase fold domain of this protein. It is thus proposed that this gene product modulates the stimulatory activity of CD4.[3]


SPG21 has been shown to interact with CD4.[1]


  1. ^ a b Zeitlmann L, Sirim P, Kremmer E, Kolanus W (Mar 2001). "Cloning of ACP33 as a novel intracellular ligand of CD4". J Biol Chem 276 (12): 9123–32. doi:10.1074/jbc.M009270200. PMID 11113139. 
  2. ^ Simpson MA, Cross H, Proukakis C, Pryde A, Hershberger R, Chatonnet A, Patton MA, Crosby AH (Oct 2003). "Maspardin Is Mutated in Mast Syndrome, a Complicated Form of Hereditary Spastic Paraplegia Associated with Dementia". Am J Hum Genet 73 (5): 1147–56. doi:10.1086/379522. PMC 1180493. PMID 14564668. 
  3. ^ a b "Entrez Gene: SPG21 spastic paraplegia 21, maspardin (autosomal recessive, Mast syndrome)". 

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