{PDOC00163}
{PS00183; UBC_1}
{PS50127; UBC_2}
{BEGIN}
*****************************************************************************
* Ubiquitin-conjugating (UBC) active site signature and core domain profile *
*****************************************************************************

Ubiquitin-conjugating enzymes  (EC  2.3.2.23)  (UBC  or  E2 enzymes) [1,2,3,4]
catalyze the covalent attachment of ubiquitin to target proteins. Ubiquitin is
conjugated to  the  target  protein  through  the  coordinated action of three
enzyme activities  designated  E1,  E2, and E3. The E1 or ubiquitin-activating
enzyme (see  <PDOC00463>)  forms,  in  an  ATP-dependent  manner,  a thioester
linkage between   its  active  site  cysteine  and  the  carboxy  terminus  of
ubiquitin. The  activated  ubiquitin moiety is then transferred from E1 to the
active site  cysteine in E2 through a trans-thiol esterification reaction. The
UBC enzyme  later  ligates  ubiquitin  directly  to substrate proteins with or
without the assistance of 'N-end' recognizing proteins (E3).

In most species there are  many forms  of UBC  (at least 9 in yeast) which are
implicated in diverse cellular functions.

The UBC core is an alpha/beta domain containing one four-stranded antiparallel
beta-sheet and  four  alpha-helices  (see  <PDB:2E2C>). Three of these helices
flank two  opposite  edges  of the sheet, and one helix lays diagonally across
one broad  face  of  the  sheet.  The  other  face  of the sheet is exposed to
solvent. One turn of a 3(10)-helix is located between the fourth strand of the
sheet and  the  second  alpha-helix. The active site cysteine is situated in a
segment between the fourth strand of the sheet and the 3(10)-helix [4].

We have  used  the  region  around  the  active  site  cysteine as a signature
pattern. We  also  developed  a profile that spans the complete catalytic core
domain.

-Consensus pattern: [FYWLSP]-H-[PC]-[NHL]-[LIV]-x(3,4)-G-x-[LIVP]-C-[LIV]-
                    x(1,2)-[LIVR]
                    [C is the active site residue]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for yeast UBC6 (DOA2).
-Other sequence(s) detected in Swiss-Prot: NONE.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Expert(s) to contact by email:
           Jentsch S.; jentsch@zmbh.uni-heidelberg.de

-Last update: April 2020 / Profile and text revised.

[ 1] Jentsch S., Seufert W., Sommer T., Reins H.-A.
     "Ubiquitin-conjugating enzymes: novel regulators of eukaryotic
     cells."
     Trends Biochem. Sci. 15:195-198(1990).
     PubMed=2193438
[ 2] Jentsch S., Seufert W., Hauser H.-P.
     "Genetic analysis of the ubiquitin system."
     Biochim. Biophys. Acta 1089:127-139(1991).
     PubMed=1647207
[ 3] Hershko A.
     "The ubiquitin pathway for protein degradation."
     Trends Biochem. Sci. 16:265-268(1991).
     PubMed=1656558
[ 4] Jiang F., Basavappa R.
     "Crystal structure of the cyclin-specific ubiquitin-conjugating enzyme
     from clam,  E2-C, at 2.0 A resolution."
     Biochemistry 38:6471-6478(1999).
     PubMed=10350465; DOI=10.1021/bi9901329

--------------------------------------------------------------------------------
PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and
distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives
(CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html
--------------------------------------------------------------------------------

{END}