r ates ▁are ▁suitable ▁for ▁such ▁a ▁wide ▁variety ▁of ▁functions ▁due ▁to ▁the ▁divers ity ▁in ▁structure ▁generated ▁from ▁mon os ac char ide ▁composition , ▁g ly cos id ic ▁link age ▁positions , ▁chain ▁branch ing , ▁and ▁c oval ent ▁modification . ▁Possible ▁c oval ent ▁modifications ▁include ▁ac et yl ation , ▁m eth yl ation , ▁ph osph ory lation , ▁and ▁sul f ation . ▁Sul f ation , ▁performed ▁by ▁car bo h yd rate ▁sul f otr ans fer ases , ▁generates ▁car bo h yd rate ▁sul f ate ▁est ers . ▁These ▁sul f ate ▁est ers ▁are ▁only ▁located ▁ext rac ell ular ly , ▁whether ▁through ▁ex cret ion ▁into ▁the ▁ext rac ell ular ▁matrix ▁( EC M ) ▁or ▁by ▁presentation ▁on ▁the ▁cell ▁surface . ▁As ▁ext rac ell ular ▁comp ounds , ▁sul f ated ▁car bo h yd r ates ▁ ▁are ▁medi ators ▁of ▁inter cell ular ▁communication , ▁cell ular ▁ad hes ion , ▁and ▁EC M ▁maintenance . ▁ ▁En zym e ▁mechanism ▁Sul f otr ans fer ases ▁catal y ze ▁the ▁transfer ▁of ▁a ▁sul fony l ▁group ▁from ▁an ▁activ ated ▁sul f ate ▁don or ▁onto ▁a ▁hydro x yl ▁group ▁( or ▁an ▁am ino ▁group , ▁although ▁this ▁is ▁less ▁common ) ▁of ▁an ▁accept or ▁mole c ule . ▁In ▁e uk ary otic ▁cells ▁the ▁activ ated ▁sul f ate ▁don or ▁is ▁