Scientists discover new pathways, proteins, and genes so rapidly that the body of knowledge in biology is already incredibly vast. And yet, even the processes we think are thoroughly well-characterized might not be so complete.
Several weeks ago, a paper published by Wan et al. from Johns Hopkins University School of Medicine reported the discovery that LRP6, a co-receptor for the well-known Wnt cell signaling pathway, was also an important regulator of the G-protein-coupled receptor/cyclic AMP pathway. LRP6 is involved in the recruitment and localization of the G-protein containing the Gαs-subunit to the plasma membrane of the cell, which makes LRP6 essential for adenylyl cyclase to be able to produce the secondary messenger cyclic AMP. Moreover, protein kinase A, the downstream effector of cyclic AMP, phosphorylates LRP6 in order to stimulate LRP6’s interaction with the G-protein. Thus, LRP6’s associated with protein kinase A amplifies the Gα signal.
Long story short, perhaps another paragraph or two might be added to the GPCR section in Lodish’s Molecular Cell Biology…
A reference to the paper:
Mei Wan, Jun Li, Katie Herbst, Jin Zhang, Bing Yu, Xiangwei Wu, Tao Qiu, Weiqi Lei, Charlotta Lindvall, Bart O. Williams, Hairong Ma, Fengjie Zhang, and Xu Cao (15 March 2011)
Sci. Signal. 4 (164), ra15. [DOI: 10.1126/scisignal.2001464]