{PDOC00257}
{PS00285; POTATO_INHIBITOR}
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* Potato inhibitor I family signature *
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The potato inhibitor I family  is  one of  the   numerous families  of  serine
proteinase  inhibitors.    Members of this protein family are found in plants;
in the seeds of  barley or beans [1,2,3], and in potato or tomato leaves where
they accumulate in response to mechanical damage [4,5]. An inhibitor belonging
to this family  is also found  in  leech [6].  It is interesting to note that,
currently, this  is the  only proteinase  inhibitor family to be found both in
plant and animal kingdoms.

Structurally these inhibitors  are  small (60 to 90 residues)  and in contrast
with other  families of protease inhibitors, they lack  disulfide bonds.  They
have a  single inhibitory site.  The consensus  pattern  we developed includes
three out of the four residues conserved in all members  of this family and is
located in the N-terminal half.

-Consensus pattern: [FYW]-P-[EQH]-[LIV](2)-G-x(2)-[STAGV]-x(2)-A
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for barley subtilisin-chymotrypsin inhibitor-2b which has Glu instead of Gly,
 and a trypsin inhibitor from the cucurbitaceae Momordica charantia [7], which
 is said  to  belong  to  the potato inhibitor I family but which shows only a
 very weak similarity with the other members of this family.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: June 1994 / Text revised.

[ 1] Svendsen I., Hejgaard J., Chavan J.K.
     Carlsberg Res. Commun. 49:493-502(1984).
[ 2] Svendsen I., Boisen S., Hejgaard J.
     Carlsberg Res. Commun. 47:45-53(1982).
[ 3] Nozawa H., Yamagata H., Aizono Y., Yoshikawa M., Iwasaki T.
     "The complete amino acid sequence of a subtilisin inhibitor from
     adzuki beans (Vigna angularis)."
     J. Biochem. 106:1003-1008(1989).
     PubMed=2628417
[ 4] Cleveland T.E., Thornburg R.W., Ryan C.A.
     Plant Mol. Biol. 8:199-207(1987).
[ 5] Lee J.S., Brown W.E., Graham J.S., Pearce G., Fox E.A., Dreher T.W.,
     Ahern K.G., Pearson G.D., Ryan C.A.
     "Molecular characterization and phylogenetic studies of a
     wound-inducible proteinase inhibitor I gene in Lycopersicon species."
     Proc. Natl. Acad. Sci. U.S.A. 83:7277-7281(1986).
     PubMed=3463966
[ 6] Seemuller U., Eulitz M., Fritz H., Strobl A.
     "Structure of the elastase-cathepsin G inhibitor of the leech Hirudo
     medicinalis."
     Hoppe-Seyler's Z. Physiol. Chem. 361:1841-1846(1980).
     PubMed=6906312
[ 7] Zeng F.-Y., Qian R.-Q., Wang Y.
     FEBS Lett. 234:35-38(1988).

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