Reactome | Oligomerization of connexins into connexons

Oligomerization of connexins into connexons

Stable Identifier

R-HSA-190704

Type

Pathway

Species

Homo sapiens

ReviewStatus

5/5

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Oligomerization of connexins into connexons

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The mechanism of connexin assembly into connexons has been well characterized. Two different types of connexons can be formed. A connexon containing six identical connexin molecules is referred to as an homomeric connexon, while a connexon containing at least two different connexin molecules is referred to as an heteromeric connexon. The connexin molecules making up an heteromeric connexon appear to belong to only one subgroup (alpha or beta); heteromeric connexons containing both alpha and beta subunits have not yet been observed. Indeed, an intrinsic signal in four amino acid positions appears to confer different physicochemical characteristics to certain connexins in the alpha and beta groups (Lagr et al., 2003). These intrinsic signals are Cx specific, however (see Gemel et al., 2006). Therefore, additional yet unknown signals are required to regulate connexin compatibility and hetero-oligomerization.
The identification of the subcellular location at which gap junction assembly occurs has proven difficult. One explanation for this difficulty may be that the location of oligomerization for each connexon varies depending upon Cx type or cell type. Oligomerization has been observed after ER membrane insertion (Cx43, Cx32, Cx26) (Falk et al., 1997; Ahmad et al., 1999; Ahmad and Evans, 2002), in the ER-Golgi-intermediate compartment (ERGIC) (Cx32) (Diez et al. 1999) and inside the trans-Goligi network (Cx43) (Musil and Goodenough, 1993).

Literature References

PubMed ID	Title	Journal	Year
7691412	Multisubunit assembly of an integral plasma membrane channel protein, gap junction connexin43, occurs after exit from the ER Musil, LS, Goodenough, DA	Cell	1993
10231375	Assembly of heteromeric connexons in guinea-pig liver en route to the Golgi apparatus, plasma membrane and gap junctions Diez, JA, Ahmad, S, Evans, WH	Eur J Biochem	1999
10191254	Synthesis and assembly of connexins in vitro into homomeric and heteromeric functional gap junction hemichannels Ahmad, S, Diez, JA, George, CH, Evans, WH	Biochem J	1999
16723732	N-terminal residues in Cx43 and Cx40 determine physiological properties of gap junction channels, but do not influence heteromeric assembly with each other or with Cx26 Gemel, J, Lin, X, Veenstra, RD, Beyer, EC	J Cell Sci	2006
12829738	Specific amino-acid residues in the N-terminus and TM3 implicated in channel function and oligomerization compatibility of connexin43 Lagree, V, Brunschwig, K, Lopez, P, Gilula, NB, Richard, G, Falk, MM	J Cell Sci	2003
9184217	Cell-free synthesis and assembly of connexins into functional gap junction membrane channels Falk, MM, Buehler, LK, Kumar, NM, Gilula, NB	EMBO J	1997
11985493	Post-translational integration and oligomerization of connexin 26 in plasma membranes and evidence of formation of membrane pores: implications for the assembly of gap junctions Ahmad, S, Evans, WH	Biochem J	2002