Disease relevance of ALB3

• We find that Alb3 can functionally complement the Escherichia coli YidC depletion strain and promote the membrane insertion of the M13 procoat and leader peptidase that were previously shown to depend on the bacterial YidC for membrane translocation [1].

High impact information on ALB3

• Integration of thylakoid proteins by the chloroplast signal recognition particle (cpSRP) posttranslational transport pathway requires the cpSRP, an SRP receptor homologue (cpFtsY), and the membrane protein ALB3 [2].
• Alb3 homologs Oxa1 and YidC have been shown to be required for the integration of newly synthesized proteins into membranes [3].
• Inactivation of a cyanobacterial gene with sequence similarity to the YidC/Oxa1p/Alb3-like domain of ARTEMIS resulted in aberrant cell division, which could be rescued by the Arabidopsis protein [4].
• ARTEMIS consists of three distinct modules: an N-terminal receptor-like region, a centrally positioned glycine-rich stretch containing a nucleoside triphosphate-binding site, and a C-terminal YidC/Oxa1p/Alb3 protein translocase-like domain [4].
• Moreover, a mutation (alb3) causing an albino phenotype was conclusively shown to be caused by insertion of the Ds element: somatic and germinal reversion of the mutation occurred in the presence of the transposase gene but not in its absence, and in three revertants the Ds had excised from its position in the mutant line [5].

Biological context of ALB3

• This identifies ARTEMIS as a functional member of the Alb3/Oxa1/YidC protein family and suggests the existence of a novel protein sorting pathway in chloroplasts which integrates polypeptides from the stroma into the inner envelope by an evolutionary conserved process [6].

Anatomical context of ALB3

• The integration of light-harvesting chlorophyll proteins (LHCPs) into the thylakoid membrane requires the integral thylakoid membrane protein ALB3, a homologue of the bacterial cytoplasmic membrane protein YidC [7].
• The integral membrane proteins Alb3, OxaI, and YidC belong to an evolutionary conserved protein family mediating protein insertion into the thylakoid membrane of chloroplasts, the inner membrane of mitochondria, and bacteria, respectively [8].

Associations of ALB3 with chemical compounds

• In addition, an association of ALB3 with the cpSecY complex was demonstrated directly by cross-linking experiments using the chemical cross-linker disuccinimidyl suberate [7].

Analytical, diagnostic and therapeutic context of ALB3

• A direct interaction of ALB3 with the cpSecY complex was demonstrated by co-immunoprecipitation experiments using digitonin-solubilized thylakoid membrane proteins and anti-cpSecY or anti-ALB3 antibodies [7].
• Furthermore, we show that most ALB3 co-fractionates with cpSecY during gel-filtration analysis and blue native gel electrophoresis, suggesting an association of ALB3 with the cpSecY complex [7].

References