Hsp22 (HSPB8) is a 196-amino acid protein that contains a central portion homologous to a highly conserved HSP-alpha crystallin domain common to all the small heat shock protein (HSP20) family members. Hsp22 is a monomeric protein which interacts with HSPB1. It displays temperature-dependent chaperone activity. The highest abundance of Hsp22 is in skeletal muscle, heart, and placenta. Mutations in the HSPB8 gene are associated with the inherited peripheral neuropathies, autosomal dominant distal hereditary motor neuropathy type IIA (dSMA) and axonal Charcot-Marie-Tooth disease type 2L (CMT2L).
Function:
Displays temperature-dependent chaperone activity.
Subunit:
Monomer. Interacts with HSPB1. Interacts with DNAJB6.
Subcellular Location:
Cytoplasm. Nucleus. Note=Translocates to nuclear foci during heat shock.
Tissue Specificity:
Predominantly expressed in skeletal muscle and heart.
DISEASE:
Defects in HSPB8 are the cause of distal hereditary motor neuronopathy type 2A (HMN2A) [MIM:158590]; also known as distal hereditary motor neuropathy type IIA or spinal Charcot-Marie-Tooth disease IIA. Distal hereditary motor neuronopathies constitute a heterogeneous group of neuromuscular disorders caused by selective impairment of motor neurons in the anterior horn of the spinal cord, without sensory deficit in the posterior horn. The overall clinical picture consists of a classical distal muscular atrophy syndrome in the legs without clinical sensory loss. The disease starts with weakness and wasting of distal muscles of the anterior tibial and peroneal compartments of the legs. Later on, weakness and atrophy may expand to the proximal muscles of the lower limbs and/or to the distal upper limbs.
Defects in HSPB8 are the cause of Charcot-Marie-Tooth disease type 2L (CMT2L) [MIM:608673]. CMT2L is an axonal form of Charcot-Marie-Tooth disease. Axonal CMT neuropathies are characterized by signs of axonal regeneration in the absence of obvious myelin alterations, normal or slightly reduced nerve conduction velocities, and progressive distal muscle weakness and atrophy.
Similarity:
Belongs to the small heat shock protein (HSP20) family.
SWISS:
Q9UJY1
Gene ID:
26353
Database links:
Entrez Gene: 26353 Human
Entrez Gene: 80888 Mouse
Entrez Gene: 113906 Rat
Omim: 608014 Human
SwissProt: Q9UJY1 Human
SwissProt: Q9JK92 Mouse
SwissProt: Q9EPX0 Rat
Unigene: 80095 Human
Unigene: 21549 Mouse
Unigene: 102906 Rat
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