********************************************
* Alpha-lactalbumin / lysozyme C signature *
********************************************

Alpha-lactalbumin [1], a milk protein, is  the  regulatory  subunit of lactose
synthetase. In the  mammary  gland,  alpha-lactalbumin  changes  the substrate
specificity of galactosyltransferase from N-acetylglucosamine to glucose.

Lysozymes (EC 3.2.1.17) [2]  act  as bacteriolytic  enzymes by hydrolyzing the
beta(1->4) bonds  between N-acetylglucosamine  and N-acetylmuramic acid in the
peptidoglycan of  prokaryotic  cell walls.   There are at least five different
classes of lysozymes [3,4]: C (chicken type), G (goose type), phage-type (T4),
fungi  (Chalaropsis), and  bacterial  (Bacillus subtilis)  but there  are  few
similarities in the sequences of the different types of lysozymes.

Alpha-lactalbumin and lysozyme C are  evolutionary related [5].  Around  35 to
40% of the residues are conserved in both proteins as well as the positions of
the four disulfide bonds (see the schematic representation).   The pattern for
this family of proteins includes  three  cysteines  involved  in  two of these
disulfide bonds (the first cysteine is linked to the third one).

                                  +-------+
                                  |     **|*******
     xxCxxxxxxxxxxCxxxxxxxxxxxxxxxCxxxxxCxCxxxxxxCxxxxxxxxxCxxxCxx
       |          |                     +--------+         |    |
       |          +----------------------------------------+    |
       +--------------------------------------------------------+

'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.

-Consensus pattern: C-x(3)-C-x(2)-[LF]-x(3)-[DEN]-[LI]-x(5)-C
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Note: these proteins belong to family 22  in  the  classification of glycosyl
 hydrolases [6].

-Last update: December 1992 / Text revised.

[ 1] Hall L., Campbell P.N.
     Essays Biochem. 22:1-26(1986).
[ 2] Concise Encyclopedia Biochemistry, Second Edition, Walter de Gruyter,
     Berlin New-York (1988).
[ 3] Weaver L.H., Grutter M.G., Remington S.J., Gray T.M., Isaacs N.W.,
     Matthews B.W.
     J. Mol. Evol. 21:97-111(1985).
[ 4] Kamei K., Hara S., Ikenaka T., Murao S.
     J. Biochem. 104:832-836(1988).
[ 5] Nitta K., Sugai S.
     Eur. J. Biochem. 182:111-118(1989).
[ 6] Henrissat B.
     Biochem. J. 280:309-316(1991).