Isoform nomenclature

Marcovina SM, Hobbs HH, Albers JJ. Relation between number of apolipoprotein(a) kringle 4 repeats and mobility of isoforms in agarose gel basis for a standardized isoform nomenclature. Clin Chein 1996 42 436-9. 

Although a uniform nomenclature for Na /H exchanger isoforms has not yet been adopted, we will refer to the amiloride-sensitive type of Na" /H exchanger that is present in the basolateral membrane of epithelia (apical membrane of placental syncytiotrophoblast) and also widely distributed in non-epithelial cells as the sensitive-type. The relatively amiloride-resistant isoform present in apical mem-... 

Myelin basic protein. In PNS myelin, MBP varies from approximately 5% to 18% of total protein, in contrast to the CNS, where it is close to 30% [ 1 ]. In rodents, the same four 21,18.5,17 and 14kDa MBPs found in the CNS are present in the PNS. In adult rodents, the 14kDa MBP is the most prominent component and is termed Pr in the PNS nomenclature. The 18.5 kDa component is present and is often referred to as the P, protein in the nomenclature of peripheral myelin proteins. Another species-specific variation in human PNS is that the major basic protein is not the 18.5 kDa isoform that is most prominent in the CNS but rather a form of about 17 kDa. It appears that MBP does not play as critical a role in myelin structure in the PNS as it does in the CNS. For example, the shiverer mutant mouse, which expresses no MBP (Table 4-2), has a greatly reduced amount of CNS myelin, with no compaction of the major dense line. By contrast, shiverer PNS has essentially normal myelin,both in amount and structure, despite the absence of MBP. This CNS/PNS difference in the role of MBP is probably because the cytoplasmic domain of P0 has an important role in stabilizing the major dense line of PNS myelin. Animals doubly deficient for P0 and MBP have a more severe defect in compaction of the PNS major dense line than P0-null mice, which indicates that both proteins contribute to compaction of the cytoplasmic surfaces in PNS myelin [23],... 

Four isoforms of PLC ((3, y, 8 and e Fig. 20-3) have been identified in the brain, with the nomenclature based upon the chronology of their discovery. The a isoform was subsequently identified as a proteolytic fragment of PLC8 (for reviews, see [10,11]). Because the lower eukaryotes such as yeast and slime molds possess only the 8 isoform, it has been suggested that the other isoforms evolved... 

Additional dysbindin-1 isoforms are likely to exist. As discussed in Section 2.2.6.1.2, there are many known and proposed transcripts of the DTNBP1 gene in humans. In addition to those encoding dysbindin-lA, -IB, and -1C, there are five for which we know the complete exon coding sequence that would encode both a CCD and a DD. They are transcripts b, c, f, g, and h in the nomenclature of the NCBI gene database Ace View. The proteins encoded by these transcripts are predicted to be 338, 334, 219, 212, and 208 aa in length. In our nomenclature, they would be dysbindin-1 isoforms D, E, F, G, and H, respectively. In the human dorsolateral prefrontal cortex, mRNA for dysbindin-lA, -IB, -1C, and -IE has been found (i.e., Ace View human DTNBP1 transcripts a, d, e, and c, respectively R. Straub, personal communication). 

Allelic variants for other CYP isoforms involved in the metabolism of drugs have been documented and in some cases effects of allelic variants have been examined. A compendium of allelic variants for human CYP isoforms in families 1, 2, 3, and 4 is available on the Web at the home page of the Human Cytochrome P450 (CYP) Allele Nomenclature Committee (http //www.cypaheles.ki.se/cypalleles.html). 

In this nomenclature, the "nonmuscle" LC17a is the more basic and the "gizzard type" smooth muscle LClTb is the more acidic isoform (Kelley et al., 1993), and therefore the LClTb of urea-PAGE corresponds to the LClTa of the 2D gel and the LClTa of the former corresponds to the LClTb of the latter. In this review, we shall refer to LClTa as the more acidic and LClTb as the more basic isoform, and will make the appropriate corrections in the data presentation of the reverse designations. 

The PPlc8 isoform is associated with the trimeric phosphatase from chicken and turkey gizzard (Okubo et al., 1993). Alessi et al. (1992) also showed the presence of this isoform (in their nomenclature it is the P-isoform). The same isoform is associated with skeletal muscle myosin (Dent etal., 1992). It is reasonable to expect that each isoform has distinctive properties, although this has not yet been demonstrated. Zhang et al. (1992) developed an expression system for the PPlc subunit and found that the four isoforms were similar with respect to inhibition by 12 and okadaic acid (Zhang et al., 1993). They required Mn2+ for full activity. The PPlc has also been expressed in the baculo-... 

Isoform Other nomenclatures Chromosomal Localization (human) Cellular localization Molecular mass (kDa)... 

NOS III e-NOS (for endothelial NOS) c-NOS (for constitutive or Ca -regulated NOS overlap with nomenclature for NOS I) ec-NOS or EC-NOS (for endothelial constitutive NOS) This isoform is constitutively expressed and its activity is regulated by Ca the prototypical enzyme is present in endothelial cells... 

Fig. 7. Diversification of SMC populations in rabbit aorta based on selective SM- and NM-MyHCpia isoform expression. In brackets is reported the nomenclature proposed by Holifield et al. [191] and Seidel et aL [193], possibly corresponding to the SMC phenotypes identified by Giuriato et al. [149],...

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