Lemon encodes an unusual receptor protein-tyrosine kinase expressed during gametogenesis in Hydra.
In a screen for receptor protein-tyrosine kinase (RTK) genes expressed during gametogenesis in the cnidarian Hydra vulgaris, we isolated a cDNA encoding Lemon, an RTK with unusual features. Lemon is orthologous to Drosophila Dtrk, chicken Klg, and human colon carcinoma kinase-4. These genes constitute an RTK class characterized by a conserved transmembrane sequence, the presence of extracellular immunoglobulin-like repeats, and the absence of the DFG motif in the kinase domain. We provide evidence that Lemon is a component of an unusual RTK signal transduction mechanism that may involve transmembrane domain-mediated interactions and may not be dependent on its own catalytic activity. Lemon transcription is dynamically regulated in interstitial cells during asexual budding and gametogenesis. Transcriptional up-regulation occurs early in spermatogenesis and oogenesis concurrent with the local accumulation of interstitial cells in the body column of sexual polyps.
Department of Biological Chemistry and the Developmental Biology Center, University of California at Irvine, 92697, USA.
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Miller
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Steele
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000378:metabolism; D005718:Gametogenesis; D006801:Humans; D006829:Hydra / Q000196:embryology*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; D008565:Membrane Proteins; D020794:Receptor Protein-Tyrosine Kinases; C413167:lemon protein, Hydra vulgaris