Caveolae are specialized lipid rafts that form flask-shaped invaginations of the plasma membrane. Many researches show that caveolae are involved in cell signaling and transport. Caveolin-1 is the major coat protein essential for the formation of caveolae. Recently, several reports indicated that the other caveolae-associated proteins, Cavins, are required for caveola formation and organization. It's worth noting that Cavin-1 could cooperate with Caveolin-1 to accommodate the structural integrity and function of caveolae. Here, we reviewed that the relationship between Cavins and Caveolins and explore the role of them in regulating caveolae.
Animals ; Caveolae ; physiology ; Caveolin 1 ; metabolism ; physiology ; Caveolins ; metabolism ; physiology ; Humans ; Membrane Proteins ; metabolism ; physiology ; RNA-Binding Proteins ; metabolism ; physiology

Membrane microparticles are shed from the plasma membrane of most eukaryotic cells when these cells were undergone activation or apoptosis, and released into the extracellular environment. Their composition depends on the cellular origin and processes triggering their formation. Several lines of evidence suggest that membrane microparticles might be able to facilitate cell-cell cross-talk and play an important roles in the regulation of survival, proliferation, differentiation, adhesion and chemotaxis of hematopoietic cells. Here, the components, mechanism of formation and the regulatory roles of membrane microparticles in hematopoiesis were reviewed.
Caveolae ; metabolism ; physiology ; Cell Membrane ; metabolism ; physiology ; Hematopoiesis ; physiology ; Humans ; Models, Biological ; R-SNARE Proteins ; metabolism ; physiology

While the field of ATP synthase research has a long history filled with landmark discoveries, recent structural works provide us with important insights into the mechanisms that links the proton movement with the rotation of the Fo motor. Here, we propose a mechanism of unidirectional rotation of the Fo complex, which is in agreement with these new structural insights as well as our more general ΔΨ-driving hypothesis of membrane proteins: A proton path in the rotor-stator interface is formed dynamically in concert with the rotation of the Fo rotor. The trajectory of the proton viewed in the reference system of the rotor (R-path) must lag behind that of the stator (S-path). The proton moves from a higher energy site to a lower site following both trajectories simultaneously. The two trajectories meet each other at the transient proton-binding site, resulting in a relative rotation between the rotor and stator. The kinetic energy of protons gained from ΔΨ is transferred to the c-ring as the protons are captured sequentially by the binding sites along the proton path, thus driving the unidirectional rotation of the c-ring. Our ΔΨ-driving hypothesis on Fo motor is an attempt to unveil the robust mechanism of energy conversion in the highly conserved, ubiquitously expressed rotary ATP synthases.
Membrane Potentials ; physiology ; Membrane Proteins ; chemistry ; metabolism ; Mitochondrial Proton-Translocating ATPases ; chemistry ; metabolism ; Protein Conformation

Animals ; Antimicrobial Cationic Peptides ; physiology ; Carrier Proteins ; physiology ; Cation Transport Proteins ; physiology ; Ceruloplasmin ; physiology ; Female ; Ferritins ; physiology ; Hemochromatosis Protein ; Hepcidins ; Histocompatibility Antigens Class I ; physiology ; Humans ; Iron ; metabolism ; Iron-Regulatory Proteins ; physiology ; Membrane Proteins ; physiology ; Placenta ; metabolism ; Pregnancy ; Transferrin ; physiology

Cation transporters play important roles in modulating the concentration of intracellular metal ions. The vacuole is an important storage organelle for many ions. Cation (Ca+)/H+ antiporters (CAXs) located at vacuolar membrane are mainly involved in the Ca2+ flux into the vacuole, and appear to be capable of transporting various divalent cations to some degree. Several CAX genes have been isolated and characterized from various plants in recent years. Four domains of plant CAXs have been identified: NRR regulates Ca2+ transport by a mechanism of N-terminal autoinhibition; Ca domain and C domain confer Ca2+ and Mn2+ specificity among CAX transporters, respectively; D domain plays a part in the regulation of cytosolic pH. AtCAXs identified in Arabidopsis thaliana are involved in the growth, development and stress adaption of plant. AtCAX3 is the mainly Ca2+/H+ transporter in response to salt stress; AtCAX2 and AtCAX4 participate in transportation and detoxicification of heavy metal ions (Cd2+, Zn2+, and Mn2+) in cells under heavy metal stress, and impact root/shoot Cd partitioning in plant. These suggest that CAX genes may be useful for nutritional enhancement of plants, and for increasing phytoremediation potential. Here, the classification, structure and function of CAXs in plants are reviewed.
Antiporters ; chemistry ; physiology ; Arabidopsis ; chemistry ; Arabidopsis Proteins ; chemistry ; physiology ; Calcium ; metabolism ; Cation Transport Proteins ; chemistry ; physiology ; Membrane Proteins ; physiology ; Metals, Heavy ; metabolism ; Plant Physiological Phenomena ; Plant Proteins ; physiology ; Plants ; chemistry ; Proton Pumps ; chemistry ; physiology ; Vacuoles ; metabolism ; physiology

Rafts, cholesterol- and sphingolipid-rich membrane microdomains, have been shown to play an important role in immune cell activation. More recently rafts were implicated in the signal transduction by members of the TNF receptor (TNFR) family. In this study, we provide evidences that the raft microdomain has a crucial role in RANK (receptor activator of NF-kappaB) signaling. We found that the majority of the ectopically expressed RANK and substantial portion of endogenous TRAF2 and TRAF6 were detected in the low-density raft fractions. In addition, TRAF6 association with rafts was increased by RANKL stimulation. The disruption of rafts blocked the TRAF6 translocation by RANK ligand and impeded the interaction between RANK and TRAF6. Our observations demonstrate that proper RANK signaling requires the function of raft membrane microdomains.
Carrier Proteins/metabolism ; Glycoproteins/*metabolism ; Human ; Membrane Glycoproteins/metabolism ; Membrane Microdomains/*metabolism ; Protein Transport/physiology ; Proteins/*metabolism ; Receptors, Cytoplasmic and Nuclear/*metabolism

OBJECTIVETo observe the changes of erythrocyte deformability in rats acclimatized to hypoxia and its molemechanism.

METHODSMale rats were randomly divided into three groups (n = 10): normal control group, acute hypoxia group and hypoxia acclimatization group. Animals were exposed to hypoxia for 0, 1, 28 d, blooded from their hearts after anaesthetized, respectively. Erythrocyte deformability, membrane fluidity, cholesterin and total lipid, lipid components of erythrocyte membrane, erythrocyte membrane ATPase and the concentrations of Na+ and Ca2+ were measured respectively. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. The different protein spots were founded by image master 2D elite and identified by mass spectrum.

RESULTS(1) In acute hypoxia group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were declined. The content of phosphatidylserines (PS), sphingomyelin (SM) in erythrocyte membrane lipids were increased, phosphatidylcholine (PC) reduced. The activity of ATP enzymes reduced and the concentration of Na+ and Ca2+ in erythrocyte increased. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. Four of the seven protein spots selected increased and three of them showed no change. (2) In hypoxia acclimatization group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were increased than those in acute hypoxia group, similar to normal group. The content of PS, SM in erythrocyte membrane lipids were reduced, PC increased. The activity of ATP enzymes induced and the concentration of Na+ and Ca2+ in erythrocyte increased after hypoxia acclimatization. Four of those protein spots mentioned increase and three declined after hypoxia acclimatization. They were respectively proved by mass spectrum to be alexin binding protein, aquaporin chip, membrane inhibitor reactive lysis, phospholipids scramblase, glucose transferase, aminophospholipid translocases, ATP-dependent floppase, the latter three proteins were associate with the overturning of erythrocyte membrane lipids.

CONCLUSIONAcute hypoxia caused the corresponding damage of erythrocyte deformability, erythrocyte membrane fluidity, erythrocyte membrane proteins erythrocyte expression, the activity of membrane ATPase and the concentration of Na+ and Ca2+ in erythrocyte. The parameters above were improved after hypoxia acclimatization, so hypoxia acclimatization effected positively in the damage to erythrocyte due to acute hypoxia. The three membrane proteins might play important roles in the deformability improved by hypoxia acclimatization, which included phospholipids scramblase, aminophospholipid translocases and ATP-dependent floppase.

Acclimatization ; physiology ; Adenosine Triphosphatases ; metabolism ; Altitude ; Animals ; Calcium ; metabolism ; Erythrocyte Deformability ; physiology ; Erythrocyte Membrane ; metabolism ; Hypoxia ; blood ; physiopathology ; Male ; Membrane Fluidity ; Phospholipid Transfer Proteins ; metabolism ; Rats ; Sodium ; metabolism

Distant metastasis is the main cause of cancer death. Tetraspanins (transmembrane 4 superfamily, TM4SF) is capable of forming transmembrane complexes with integrin family participating in cell adhesion, migration and tumor metastasis. This review elucidates the structure of tetraspanins and its function in regulating metastasis as form of multimolecular transmembrane complexes with integrin.
Cell Adhesion ; Humans ; Integrins ; chemistry ; metabolism ; physiology ; Membrane Proteins ; chemistry ; metabolism ; physiology ; Neoplasm Metastasis ; Neoplasms ; metabolism ; pathology ; Tetraspanins

Acute-Phase Proteins ; physiology ; Carrier Proteins ; physiology ; Humans ; Membrane Glycoproteins ; physiology ; Receptors, Cell Surface ; physiology ; Receptors, Immunologic ; physiology ; Receptors, Scavenger ; Sepsis ; metabolism ; physiopathology ; Signal Transduction ; Toll-Like Receptors

OBJECTIVETo explore the effect of substance P (SP) on the functional proteins on plasma membrane of neutrophil (Np).

METHODThe response of Np to SP was examined by measuring the level of respiratory burst, the activities of ACP and ALP, the fluoroscopy intensity of CR3, CD45 and FM-LP.

RESULTSIt was found that SP could increase respiratory burst of Np, decrease the activity of acid phosphatase (ACP), but had no effect on alkaline phosphatase (ALP). SP could also promote the amount of CD45, complement receptor type 3 (CR3) and N-Formyl-Met-Leu-Phe (FMLP) receptors.

CONCLUSIONThe results showed that the effects of SP on functional proteins in human Np membrane were universality and diversity. It implied that SP could affect various inflammation responses in Np.

Acid Phosphatase ; metabolism ; Humans ; Membrane Proteins ; physiology ; Neutrophils ; metabolism ; Respiratory Burst ; Substance P ; pharmacology