The parades of how the Golgi and other organelles can sort a continuous flu
x of protein and lipid but maintain temporal and morphological stability re
mains unresolved, Recent discoveries highlight a role for the cytoskeleton
in guiding the structure and dynamics of organelles. Perhaps one of the mor
e striking, albeit less expected, of these discoveries is the recognition t
hat a spectrin skeleton associates with many organelles and contributes to
the maintenance of Golgi structure and the efficiency of protein traffickin
g in the early secretory pathway, Spectrin interacts directly with phosphoi
nositides and with membrane proteins. The small GTPase ARF, a key player in
Golgi dynamics, regulates the assembly of the Golgi spectrin skeleton thro
ugh its ability to control phosphoinositide levels in Golgi membranes, wher
eas adapter molecules such as ankyrin link spectrin to other membrane prote
ins. Direct interactions of spectrin with actin and centractin (ARP1) provi
de a link to dynein, myosin and presumably other motors involved with intra
cellular transport. Building on the recognized ability of spectrin to organ
ize macromolecular complexes of membrane and cytosolic proteins into a mult
ifaceted scaffold linked to filamentous structural elements (termed linked
mosaics), recent evidence supports a similar role for spectrin in organelle
function and the secretory pathway. Two working models accommodate much of
the available data: the Golgi mesh hypothesis and the spectrin ankyrin ada
pter protein tethering system (SAATS) hypothesis.