AS2 Transcription Factor Family
The LOB domain contains conserved blocks of amino acids that identify the LBD gene family. In particular, a conserved
C-x(2)-C-x(6)-C-x(3)-C motif, which is defining feature of the LOB domain, is present in all LBD proteins. It is possible
that this motif forms a new zinc finger.
The lateral organ boundaries (LOB) gene is expressed at the adaxial base of initiating lateral organs and encodes a
plant-specific protein of unknown function. The N-terminal one half of the LOB protein contains a conserved approximately
100-amino acid domain (the LOB domain) that is present in 42 other Arabidopsis thaliana proteins and in proteins from a
variety of other plant species. Genes encoding LOB domain (LBD) proteins are expressed in a variety of temporal- and
tissue-specific patterns, suggesting that they may function in diverse processes.
The ASYMMETRIC LEAVES2 (AS2) gene of Arabidopsis thaliana is involved in the establishment of the leaf venation system,
which includes the prominent midvein, as well as in the development of a symmetric lamina. The gene product also represses
the expression of class 1 knox homeobox genes in leaves. We have characterized the AS2 gene, which appears to encode a novel
protein with cysteine repeats (designated the C-motif) and a leucine-zipper-like sequence in the amino-terminal half of the
primary sequence. The Arabidopsis genome contains 42 putative genes that potentially encode proteins with conserved amino
acid sequences that include the C-motif and the leucine-zipper-like sequence in the amino-terminal half. Thus, the AS2
protein belongs to a novel family of proteins that we have designated the AS2 family. Members of this family except AS2 also
have been designated ASLs (AS2-like proteins). Transcripts of AS2 were detected mainly in adaxial domains of cotyledonary
primordia. Green fluorescent protein-fused AS2 was concentrated in plant cell nuclei. Overexpression of AS2 cDNA in
transgenic Arabidopsis plants resulted in upwardly curled leaves, which differed markedly from the downwardly curled leaves
generated by loss-of-function mutation of AS2. Our results suggest that AS2 functions in the transcription of a certain
gene(s) in plant nuclei and thereby controls the formation of a symmetric flat leaf lamina and the establishment of a
prominent midvein and other patterns of venation.
Notes: AS2 family was missed in PlnTFDB.
84 predicted AS2 TF peptide,
CDS, and cDNA sequences;
blast HSP, and multiple sequence alignment.
Phylogeny trees in radiation and circle formats.
25 AS2 protein and DNA sequences with
annotations for soybean in PlantTFDB. Most are partial sequences.
Last updated by Dr. Jeff Chen on June 15, 2009.
