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  • XVI.A.2.f. PSI-G
  • Sequences of PSI-G
  • Sequence Similarity Search for PSI-G

    XVI.A.2.f. PSI-G

    The PSI-G polypeptide is an integral membrane protein (for a general review see Andersen and Scheller, 1993). It has been characterized mainly by analysis of c-DNA clones of spinach, C. reinhardtii and barley. It has an apparent molecular mass of 9 kDa in barley and a calculated molecular mass of 10.8 kDa from the cDNA clone. In barley, it is N-terminally blocked to amino acid sequencing.

    The transit peptide sequences are characteristics of proteins targeted to stromal or integral membrane locations. The transmembrane helical profile of the spinach polypeptide (Antheprot protocol) suggests the presence of three membrane-spanning helices (Rebeiz, unpublished). The segments connecting the transmembranes helixes appear to be hydrophilic segments.

    In barley the PSI-G polypeptide appears to be tightly bound to the PSI-A/PSI-B hetrodimer, which suggests in turn a fuction in the organization of the PSI core

    A query for psaG addressed to the various protein databases listed in the Biology Workbench, yielded 10 records which are depicted under Sequenced PSI-G. These sequences can be used for Sequence Similarity Searches or other manipulations using one of several routines described in the Biology Workbench or elsewhere (see AntheproW which can be downloaded via anonymous ftp from: ibcp.fr; pub/Antheprot/Windows/anthe 3_1 directory). For example a Blast Sequence Similarity Search of spinach PSI-G addressed to the Biology Workbench (SwissProt database) is depicted below.

    Sequences of PSI-G

    Click on Sequences to view the sequences of PSI-G retrieved from various protein sequence databases by the Biology Workbench.

    Sequence Similarity Search for PSI-G

    Click on Sequence Similarity Search to view the Blast sequence similarity search results of barley PSI-G from the Biology workbench (SwissProt database).

    References

    1. Andersen, B. and H. V. Scheller (1993). Structure, Function and Assembly of photosystem I. In: Pigment-Protein Complexes In Plastids: Synthesis and Assembly . C. Sundqvist and M. Ryberg, (eds.), p 383-417, Academic Press, New York.

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