Membrane Associated Guanylate Kinase With Inverted Structure 1 (MAGI1)

MAGI1 belongs to the membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins that assemble multimolecular complexes at subcellular membrane sites of polarized epithelial cells and neurons.

The predicted 1,171-amino acid protein has an N-terminal GUK domain, followed by 2 WW domains and 5 PDZ domains. Alternative splicing generates at least 3 transcripts that encode isoforms with unique C termini. Northern blot analysis revealed multiple Magi1 transcripts in many tissues. Cell fractionation and Western blot analyses showed that a 148-kD isoform containing nuclear localization signals in its C terminus was located predominantly in the nucleus. A 137-kD isoform was found primarily in membrane and cytoplasmic fractions.