pfam03073: TspO_MBR (this model, PSSM-Id:281118 is obsolete and has been replaced by 460795)
TspO/MBR family
Tryptophan-rich sensory protein (TspO) is an integral membrane protein that acts as a negative regulator of the expression of specific photosynthesis genes in response to oxygen/light. It is involved in the efflux of porphyrin intermediates from the cell. This reduces the activity of coproporphyrinogen III oxidase, which is thought to lead to the accumulation of a putative repressor molecule that inhibits the expression of specific photosynthesis genes. Several conserved aromatic residues are necessary for TspO function: they are thought to be involved in binding porphyrin intermediates. In, the rat mitochondrial peripheral benzodiazepine receptor (MBR) was shown to not only retain its structure within a bacterial outer membrane, but also to be able to functionally substitute for TspO in TspO- mutants, and to act in a similar manner to TspO in its in situ location: the outer mitochondrial membrane. The biological significance of MBR remains unclear, however. It is thought to be involved in a variety of cellular functions, including cholesterol transport in steroidogenic tissues.
Jiyao W et al.(2023). "The conserved domain database in 2023.",