A conserved gene family encodes transmembrane proteins with fibronectin, immunoglobulin and leucine-rich repeat domains (FIGLER).
BACKGROUND
In mouse the cytokine interleukin-7 (IL-7) is required for generation of B lymphocytes, but human IL-7 does not appear to have this function. A bioinformatics approach was therefore used to identify IL-7 receptor related genes in the hope of identifying the elusive human cytokine.


RESULTS
Our database search identified a family of nine gene candidates, which we have provisionally named fibronectin immunoglobulin leucine-rich repeat (FIGLER). The FIGLER 1-9 genes are predicted to encode type I transmembrane glycoproteins with 6-12 leucine-rich repeats (LRR), a C2 type Ig domain, a fibronectin type III domain, a hydrophobic transmembrane domain, and a cytoplasmic domain containing one to four tyrosine residues. Members of this multichromosomal gene family possess 20-47% overall amino acid identity and are differentially expressed in cell lines and primary hematopoietic lineage cells. Genes for FIGLER homologs were identified in macaque, orangutan, chimpanzee, mouse, rat, dog, chicken, toad, and puffer fish databases. The non-human FIGLER homologs share 38-99% overall amino acid identity with their human counterpart.


CONCLUSIONS
The extracellular domain structure and absence of recognizable cytoplasmic signaling motifs in members of the highly conserved FIGLER gene family suggest a trophic or cell adhesion function for these molecules.
Munfus
Delicia L
DL
Division of Developmental and Clinical Immunology, University of Alabama at Birmingham, Birmingham, AL 35294-3300, USA. dlmunfus@uasom.uab.edu
Haga
Christopher L
CL
Burrows
Peter D
PD
Cooper
Max D
MD
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D005353:Fibronectins / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics*; D000090263:Leucine-Rich Repeat Proteins; D005810:Multigene Family; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000235:genetics*; D020395:Receptors, Interleukin-7 / Q000235:genetics*; D017385:Sequence Homology; D013045:Species Specificity
D005353:Fibronectins; D007136:Immunoglobulins; D000090263:Leucine-Rich Repeat Proteins; D011506:Proteins; D020395:Receptors, Interleukin-7