Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.59 (MIP)
 4,906 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

17 members of MIP family from bacteria, yeast, plants and animals are compared in this review. These proteins appear to function in (1) water channels (CHIP, WCH-CD, MIWC, AQP3, gTIP, RD28, TobRB7), (2) neurogenesis (Bib), (3) small-molecule-permeating channels (MIP, AQP3, NOD, Glpf), (4) unknown function (WCH-3, AtRB7, Pea R7A, FPS1). However, the biological functions are not well established. The most conserved residues in the first and the second halves of all MIP family proteins are asparagine-proline-alanine (NPA) sequences in the loops (NPA boxes). This structural similarity may lead to functional similarity (water and/or small molecule permeation). This signature sequence for the MIP family will facilitate the identification of new protein members of this family.
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PMID:[Water channel family proteins]. 753 36

A 1.8-kb cDNA clone (designed hKID, gene symbol AQP2L) with homology to the aquaporins was isolated from a human kidney cDNA library. The longest open reading frame of 846 bp encoded a 282-amino-acid hydrophobic protein that contained the conserved NPA motifs of MIP family members. Cell-free translation produced a nonglycosylated protein migrating at 29 kDa. Amino acid alignment showed the greatest homology of hKID to human MIP (48% identity) and AQP-2 (52%), with lesser homology to human MIWC (AQP-4, 34%), CHIP28 (AQP-1, 38%), and GLIP (AQP-3, 22%). Northern blot analysis revealed a 2.2-kb transcript expressed only in human kidney. PCR/Southern blot analysis of human kidney cDNA using primers flanking the hKID coding sequence revealed expression of a full-length mRNA and short transcripts with partial exon 1 and partial exon 4 deletions. Expression of hKID cRNA in Xenopus oocytes did not increase glycerol or urea permeability, but increased osmotic water permeability from (2.8 +/- 0.5) x 10(-4) to (7.4 +/- 0.7) x 10(-4) cm/s (10 degrees C) in a mercurial-sensitive manner. Sequence comparison of hKID cDNA with a cloned 21-kb genomic DNA indicated three introns (lengths 0.7, 0.25, and 0.4 kb) separating four exons with boundaries at amino acids 121, 174, and 201. The hKID promoter was identified and contained TATA, SP1, E-box, and AP1 and AP2 elements; primer extension revealed hKID transcription initiation 654 bp upstream from the translational initiation site. Genomic Southern blot indicated a single-copy hKID gene. PCR analysis of a human/rodent somatic hybrid panel localized the hKID gene to chromosome 12. Chromosomal fluorescence in situ hybridization mapped the hKID (AQP2L) gene to chromosome locus 12q13, the same location as the AQP. 2 and MIP genes. The high sequence homology, similar genomic structure, and identical chromosomal loci of hKID, MIP, and AQP-2 suggest a MIP family gene cluster at chromosome locus 12q13. Further work is needed to establish the physiological significance of hKID.
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PMID:cDNA cloning and gene structure of a novel water channel expressed exclusively in human kidney: evidence for a gene cluster of aquaporins at chromosome locus 12q13. 881 90