9.B.94 The Male Sterility-Associated Mitochondrial Protein (MSMP) Family
In higher plants, male reproductive (pollen) development is known to be disrupted in a class of mitochondrial mutants termed cytoplasmic male sterility (CMS). ORF129 accumulates in flower, root and leaf mitochondria, and is primarily present in the matrix and is loosely associated with the inner mitochondrial membrane (Yamamoto et al. 2008). Transgenic expression of ORF129 resulted in male sterility, suggesting that it is responsible for the male-sterile phenotype in sugar beets.
This protein of 129 aas has 1 putative TMS, but its mechanism of action is unknown. Other homologues are found in subfamily 9.B.94.1. Proteins in subfamilies 9.B.94.2 and 3 may be non-homologous to ORF129.