Identification and cDNA cloning of a novel human mosaic protein, LGN, based on interaction with G alpha i2

Gene. 1996 Nov 28;181(1-2):39-43. doi: 10.1016/s0378-1119(96)00456-8.


We have used the yeast two-hybrid system to identify proteins that interact with the alpha-subunit of the heterotrimeric GTP-binding protein, Gi2. We screened a human B cell cDNA library with full-length G alpha i2 and isolated four positive colonies, one of which expressed the 44-kDa COOH terminus of a previously unrecognized 677-amino acid (aa) protein. A full-length clone was isolated from a HeLa cell cDNA library. The deduced protein contains 10 Leu-Gly-Asn repeats, and thus we named it LGN. Computer analysis indicates that LGN is a mosaic protein with seven repeated sequences of about 40 aa in length at its N-terminal end, and four repeated sequences of about 34 aa at its C-terminal end. Each of the two repeat regions shows substantial similarity to proteins found in other organisms. RT-PCR analysis of human tissues showed that the mRNA of LGN was ubiquitously expressed. The specificity of interaction between G alpha i2 and LGN was confirmed by an in vitro binding assay using recombinant proteins. These data indicate that the yeast two-hybrid system can identify novel proteins, such as LGN, that interact with G alpha proteins. As a mosaic protein, LGN shows similarity with portions of proteins from many species and thus may define a new protein family.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cloning, Molecular
  • Computing Methodologies
  • DNA
  • DNA, Complementary
  • GTP-Binding Proteins / metabolism*
  • Glutathione Transferase / genetics
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Sequence Homology, Amino Acid
  • Tissue Distribution


  • Carrier Proteins
  • DNA, Complementary
  • GPSM2 protein, human
  • Intracellular Signaling Peptides and Proteins
  • Recombinant Fusion Proteins
  • DNA
  • Glutathione Transferase
  • GTP-Binding Proteins

Associated data

  • GENBANK/U54999