Small muscle protein X-linked (SMPX)

Small muscle protein X-linked (SMPX) is a 9.6 kDa protein expressed predominantly in striated muscle (skeletal and cardiac) and, at lower levels, in smooth muscle-rich tissues. SMPX is involved in the regulation of muscle cells’ structural and functional adaptation during growth, differentiation, and repair. It is stretch-responsive, playing a role in mechanical stress responses in muscle cells and possibly in inner ear cells, explaining its association with X-linked sensorineural hearing loss. SMPX lacks classical functional domains found in receptors, enzymes, or channels; instead, it is considered a regulatory and structural protein. Transcription of SMPX is regulated by muscle-specific transcription factors (such as NOR-1, MEF2, MyoD, and Nkx2-5 in the heart). SMPX does not currently have any direct clinical application as a drug target, nor does it serve as a validated biomarker[6][1][2][3].

Other names

Small muscular proteinStretch-responsive skeletal muscle proteinDFNX4DFN6MPD7Chisel (Csl)SRMX