The various zein cDNA and genomic clones that have been isolated have each been given a name by the laboratory that first isolated the clone. This has resulted in a number of different naming systems. We propose that a new nomenclature based on the concept of zein subfamilies be used. A zein subfamily refers to a subgrouping of closely related zein genes, mRNAs and proteins whose members are more closely related in their nucleotide sequences (and amino acid sequences) to one another than they are to members of another subfamily (Rubenstein, Maize for Biological Research, W. F. Sheridan, pp. 189-195, 1982).
So far we have identified 5 subfamilies and propose now to label these SF1, SF2, SF3, SF4, and SF5 (Messing et al., Genetic Engineering of Plants, T. Kosuge, C. P. Meredith, and A. Hollaender, eds., pp. 211-227, 1983). We have determined the nucleotide sequence of representative cDNA clones for each of these subfamilies; they are A20, A30, B59, B49, and B36, respectively. All of these cDNA clones were obtained from IHP zein mRNA (Burr et al., J. Mol. Biol. 154:33-49 1982).
We propose that the various clones be renamed so as to indicate their subfamily, origin (inbred line and clone type--cDNA or genomic), and common laboratory name. For example, the cDNA clones A20, A30, B59, B49, and B36 obtained from IHP zein mRNA will be termed SF1(IHP-c)A20, SF2(IHP-c)A30, SF3(IHP-c)B59, SF4(IHP-c)B49, and SF5(IHP-c)B36, respectively. The genomic clones Z4 and Z7 isolated from W22 DNA would be termed SF2(W22-g)Z4 and SF4(W22-g)Z7, respectively since Z4 and A30 are in the same subfamily (SF2) and Z7 and B49 are in subfamily SF4.
The table represents a compilation of the zein cDNA and genomic clones which have been described in publications from many different laboratories. The rows for the subfamilies are divided by a horizontal line. The clones whose names appear above the line have been sequenced, and hence their membership within a given subfamily has been verified. Those clones whose names appear below the line have been tentatively classified into a given subfamily on the basis of hybridization data. As additional zein subfamilies and zein clones are characterized they can be fitted into this scheme.
Irwin Rubenstein and Daniel E. Geraghty
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