Mitochondrion role in molecular basis of cytoplasmic male sterility.

Cytoplasmic male sterility and its fertility restoration via nuclear genes offer the possibility to understand the role of mitochondria during microsporogenesis. In most cases rearrangements in the mitochondrial DNA involving known mitochondrial genes as well as unknown sequences result in the creation of new chimeric open reading frames, which encode proteins containing transmembrane domains. So far, most of the CMS systems have been characterized via restriction fragment polymorphisms followed by transcript analysis.

Synthetic peptides containing a conserved sequence motif of the Id protein family modulate vascular smooth muscle cell phenotype.

Modulation of smooth muscle cells to a proliferating and migrating phenotype with downregulated alpha-actin expression is observed upon vascular lesion formation. The Id proteins (inhibitors of cell differentiation) play a role in the development of this phenotype. In contrast, synthetic peptides based on a conserved 11-residue Id sequence trigger the switch to a contractile phenotype that shows reduced cell growth and migration, increased expression of alpha-actin and decreased Id protein levels.

The barley plastome mutant CL2 affects expression of nuclear and chloroplast housekeeping genes in a cell-age dependent manner.

The barley plastome mutant CL2 (cytoplasmic line 2) carries a point mutation in the infA gene, a homologue of the bacterial gene for the conserved translation initiator factor 1 (IF1). The function of infA in plastids is not known. The mutation in CL2 leads to a temporal chlorophyll deficiency in the primary leaf blade that is normalised in the basal and middle parts during further development.

A short Id2 protein fragment containing the nuclear export signal forms amyloid-like fibrils.

The negative regulator of DNA-binding/cell-differentiation Id2 is a small protein containing a central helix-loop-helix (HLH) motif and a C-terminal nuclear export signal (NES). Whereas the former is essential for Id2 dimerization and nuclear localization, the latter is responsible for the transport of Id2 from the nucleus to the cytoplasm. Whereas the isolated Id2 HLH motif is highly helical, large C-terminal Id2 fragments including the NES sequence are either unordered or aggregation-prone.

Synthesis and conformational analysis of Id2 protein fragments: impact of chain length and point mutations on the structural HLH motif.

The Id proteins are negative regulators of several basic-helix-loop-helix (HLH) transcription factors, including the ubiquitous E factors and the tissue-specific myogenin-regulating factors. Id1 through Id4 contain highly identical HLH domains but different N- and C-terminal extensions. Beside the heterodimerization with the parent HLH factors, Id2 was shown to additionally interact with the retinoblastoma protein and to be overexpressed in neuroblastoma.