http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Molecular characterization of the patatin multigene family of potato
xi, 84 leaves : illustrations (some folded) ; 29 cm
A cDNA library was constructed from poly A mRNA isolated from membrane-bound polyribosomes of developing tubers. From this library, two groups of clones for the major tuber protein, patatin, were isolated. The complete sequence of two of these clones, pGM01 and pGM203, was determined. They are 98% homologous and correspond to the two major species of patatin identified by amino-terminal polypeptide sequence analysis. Both encode proteins of 363 amino acids with an additional 23 amino acid signal sequence. Patatin mRNA is approximately 1550 nucleotides in length and is present in large amounts in tubers, in trace amounts in roots, but is not present in leaves or stems. Potato DNA was used to construct genomic libraries from which 30 patatin genomic clones were isolated. All of these exhibited different restriction patterns, but could be divided into two classes based on the presence (Class II) or absence (Class I) of a 22 bp sequence within the 5'untranslated region. The complete DNA sequence of the Class I clone, PS20, the Class II clones SA10C and SB6B, and the 5' flanking sequence of seven additional clones was determined. The transcribed region of PS20 spans 3197 bp and is divided by six introns. The seven exons encode a transcript which is identical to the cDNA, pGM203. SB6B and SA10C both are pseudogenes which contain frameshift mutations. The 5' flanking sequences of both Class I and II patatin genes are highly homologous to position -87 and then diverge. This conserved region contains the CAAT and TATA homologies as well as a homology to the core enhancer sequence. Within a class there are additional large regions of homology, but differences exist that allow the patatin genes to be further divided into several discrete subclasses. S1 nuclease protection experiments with both Class I and Class II probes has shown that Class I transcripts are the predominant species present in tubers. Class II transcripts are present in tubers, but are 50-100 fold less abundant. In roots, Class II transcripts are the predominant species and there are few, if any, Class I transcripts.
Includes bibliographical references (leaves 80-83).