PT  - JOURNAL ARTICLE
AU  - Iztok Urbančič
AU  - Lisa Schiffelers
AU  - Edward Jenkins
AU  - Weijian Gong
AU  - Ana Mafalda Santos
AU  - Falk Schneider
AU  - Caitlin O’Brien-Ball
AU  - Mai Tuyet Vuong
AU  - Nicole Ashman
AU  - Erdinc Sezgin
AU  - Christian Eggeling
TI  - Aggregation and immobilisation of membrane proteins interplay with local lipid order in the plasma membrane of T cells
AID  - 10.1101/2020.12.22.422352
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.12.22.422352
4099  - http://biorxiv.org/content/early/2020/12/22/2020.12.22.422352.short
4100  - http://biorxiv.org/content/early/2020/12/22/2020.12.22.422352.full
AB  - The quest for understanding of numerous vital membrane-associated cellular processes, such as signalling, has largely focussed on the spatiotemporal orchestration and reorganisation of the identified key proteins, including their binding and aggregation. Despite strong indications of the involvement of membrane lipid heterogeneities, historically often termed lipid rafts, their roles in many processes remain controversial and mechanisms elusive. Taking activation of T lymphocytes as an example, we here investigate membrane properties around the key proteins – in particular the T cell receptor (TCR), its main kinase Lck, and phosphatase CD45. We determine their partitioning and co-localisation in passive cell-derived model membranes (i.e. giant plasma-membrane vesicles, GPMVs), and explore their mobility and local lipid order in live Jurkat T cells using fluorescence correlation spectroscopy and spectral imaging with polarity-sensitive membrane probes. We find that upon aggregation and partial immobilisation, the TCR changes its preference towards more ordered lipid environments, which can in turn passively recruit Lck. We observe similar aggregation-induced local membrane ordering and recruitment of Lck also by CD45, as well as by a membrane protein of antigen-presenting cells, CD86, which is not supposed to interact with Lck directly. This highlights the involvement of lipid-mediated interactions and suggests that the cellular membrane is poised to modulate the frequency of protein encounters according to their aggregation state and alterations of their mobility, e.g. upon ligand binding.Competing Interest StatementThe authors have declared no competing interest.