Identification and characterization of two novel splice forms of GRIP1 in the rat brain.
We cloned two novel alternatively-spliced mRNA isoforms of glutamate receptor interacting protein 1 (GRIP1) which we named GRIP1d and GRIP1e 4-7. GRIP1d is a 135 kDa, 7-PDZ-domain variant of GRIP1, containing the 12 amino acid C-terminus originally described for the 4-PDZ-domain GRIP1c 4-7. GRIP1e 4-7 is a 75 kDa 4-PDZ-domain variant of GRIP1, containing the 12 amino acid C-terminus originally described for the 7-PDZ-domain GRIP1a/b. Northern blots indicated that GRIP1d mRNA is 5.1 kb long and abundant in brain. An antibody to the C-terminus of the 75 kDa GRIP1c 4-7 also recognized an abundant 135 kDa protein, consistent with the predicted size of GRIP1d. Similarly, an antibody to the C-terminus of the 135 kDa GRIP1a/b also recognized a low abundance 75 kDa protein, consistent with the predicted size of GRIP1e 4-7. Immunocytochemistry of hippocampal cultures and intact brain using these antibodies showed that (i) these isoforms are present in both GABAergic and glutamatergic synapses, and (ii) the isoforms co-localize in individual synapses. While GRIP1a/b isoforms are abundant in interneurons and highly concentrated in GABAergic presynaptic terminals, the isoforms recognized by the antibody to the C-terminus common to GRIP1c 4-7 and GRIP1d are much less abundant in interneurons and preferentially concentrate at the postsynaptic complex.
Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269-3156, USA.
Erik I
EI
Charych
Rongwen
R
Li
David R
DR
Serwanski
Xuejing
X
Li
Celia P
CP
Miralles
Noelia
N
Pinal
Angel L
AL
De Blas
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern / Q000379:methods; D001921:Brain / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D003001:Cloning, Molecular / Q000379:methods; D000076122:Disks Large Homolog 4 Protein; D004622:Embryo, Mammalian; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron / Q000379:methods; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment / Q000379:methods; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism
D002352:Carrier Proteins; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; C491308:Grip1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D050598:Vesicular Glutamate Transport Protein 1; D005968:Glutamate Decarboxylase