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Summary: Chloroplast SecA homolog: required for thylakoid protein targeting via the ATP-dependent "sec" pathway. A tha1 mutant allele is pale green, with high leaf chlorophyll fluorescence, and is seedling lethal due to decreased levels of many thylakoid proteins.
Image: mutant leaf color indicated on a seedling leaf color scale
First reported: Voelker and Barkan 1995.
Key Alleles
tha1-ref::Mu1 (or tha1-m1) Mu1 insertion in an intron, 19 bp away from 5'splice junction. Pale green, high leaf chlorphyll fluorescence, seedling lethal phenotype, with occasional green sectors.
Map Location
RFLP mapping to chromosome 3 (Voelker et al 1997; Davis et al. 1999).
Gene Product
Chloroplast SecA homolog; cp-SecA. Confirmation based on sequence similiarity and mutant protein accumulation.
Expression
Functions in etioplasts and chloroplasts (Voelker et al. 1997).
References
Davis GL, McMullen MD, Baysdorfer C, Musket T, Grant D, Staebell M, Xu G, Polacco M, Koster L, Melia-Hancock S, Houchins K, Chao S, Coe EH Jr. (1999) A maize map standard with sequenced core markers, grass genome reference points and 932 expressed sequence tagged sites (ESTs) in a 1736-locus map. Genetics 152(3):1137-1172. PUBMED
Settles AM, Baron A, Barkan A, Martienssen RA (2001) Duplication and suppression of chloroplast protein translocation genes in maize. Genetics 157(1):349-360. PUBMED
Voelker R, Barkan, A (1995) Two nuclear mutations disrupt distinct pathways for targeting proteins to the chloroplast thylakoid. EMBO J 14: 3905-3914. PUBMED
Voelker R, Mendel-Hartvig J, Barkan A (1997) Transposon-disruption of a maize nuclear gene, tha1, encoding a chloroplast SecA homologue: in vivo role of cp-SecA in thylakoid protein targeting. Genetics 145: 467-478. PUBMED
Links: MGDB tha1 NCBI: tha1 UniProt: O24589