Even after decades of research, a comprehensive mechanism that elucidates the underpinnings of signalling through the cell membrane is still elusive. Here, we address a simple question “how do the ectodomain of a membrane-associated protein consisting of multiple domains and connected by flexible linkers stand ‘upright’ on the membrane?”. Our analysis based on large amount of available functional and structural data, looking for a pattern of association of these molecules in the crystal structures and with the concept that ‘random things seldom repeat’ lead to a surprisingly interesting and consistent observation that the weak cis interaction mediated ordered array of constitutively expressed signalling molecules not only support their ‘upright’ orientation but also bury their ligand-binding surface to avoid spurious signaling in the non-signalling resting state. With CD4, pMHCII, CD2 and TNFR1 as examples, we show that the observed association of molecules also correlate well with their functional role. Further, our model reconciles the long-standing controversies related to these molecules and appear to be generic enough to be applied to other signalling molecules

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T‐cell co‐stimulation through CD28/CTLA4:B7‐1/B7‐2 axis is one of the extensively studied pathways that resulted in the discovery of several FDA‐approved drugs for autoimmunity and cancer. However, many aspects of the signaling mechanism remain elusive, including oligomeric association and clustering of B7‐2 on the cell surface. Here, we describe the structure of the IgV domain of B7‐2 and its cryptic association into 1D arrays that appear to represent the pre‐signaling state of B7‐2 on the cell membrane. Super‐resolution microscopy experiments on heterologous cells expressing B7‐2 and B7‐1 suggest, B7‐2 form relatively elongated and larger clusters compared to B7‐1. The sequence and structural comparison of other B7 family members, B7‐1:CTLA4 and B7‐2:CTLA‐4 complex structures, support our view that the observed B7‐2 1D zipper array is physiologically important. This observed 1D zipper‐like array also provides an explanation for its clustering, and upright orientation on the cell surface, and avoidance of spurious signaling.