The glycoprotein hormones are a family of conserved heterodimeric proteins which share a common alpha subunit but differ in their hormone-specific beta subunits. We used chimeras of human chorionic gonadotropin (hCG) and luteinizing hormone (hLH) beta subunits to identify residues which enable monoclonal antibodies (mAb) to distinguish the two hormones. The LH beta-CG beta chimeras appeared to ...

Physiological studies indicate that voltage-sensitive calcium channels are regulated by cAMP and protein phosphorylation. The calcium antagonist receptor of the voltage-sensitive calcium channel from transverse-tubule membranes consists of three subunits, designated alpha, beta, and gamma. The catalytic subunit of cAMP-dependent protein kinase phosphorylates both the alpha and beta subunits of ...

We immunized rabbits with purified guanine nucleotide-binding proteins (G proteins) from bovine brain and obtained an antiserum, RV3, that reacts specifically with the alpha subunit (39 kDa) of a G protein of unknown function, termed Go, as well as with the beta subunit (35 kDa) common to all G proteins. RV3 showed no crossreactivity with the alpha subunits of the stimulatory (Gs) or inhibitory...

Subunit assembly plays an essential role in the maturation of oligomeric proteins. In this study, we have characterized the main structural and functional consequences of the assembly of alpha and beta subunits of Na,K-ATPase. Xenopus oocytes injected with alpha and/or beta cRNA were treated with brefeldin A, which permitted the accumulation of individual subunits or alpha-beta complexes in the...

Lymphocyte function associated antigen 1 (LFA-1) is a leukocyte cell adhesion protein. We have studied a novel human immunodeficiency disease in which LFA-1 and two other proteins which share the same beta subunit are lacking from the surface of leukocytes. The basis of the inherited defect in cell surface expression of both the alpha and beta subunits of LFA-1 was determined by somatic cell fu...

The beta(2) subunit of the large conductance Ca(2+)- and voltage-activated K(+) channel (BK(Ca)) modulates a number of channel functions, such as the apparent Ca(2+)/voltage sensitivity, pharmacological and kinetic properties of the channel. In addition, the N terminus of the beta(2) subunit acts as an inactivating particle that produces a relatively fast inactivation of the ionic conductance. ...

Conformational change in the integrin extracellular domain is required for high affinity ligand binding and is also involved in post-ligand binding cellular signaling. Although there is evidence to the contrary, electron microscopic studies showing that ligand binding triggers alpha- and beta-subunit dissociation in the integrin headpiece have gained popularity and support the hypothesis that h...